What does breaking the fetter 'Clinging to rites and rituals' actually mean? The second fetter to break when one becomes a stream entrant is given as 'Clinging to rites and rituals'. I've always found that one a little puzzling. How do you know if you are clinging to a ritual? What would be the signs of it? Does the fetter apply exclusively to Buddhist rituals or does it apply to the little rituals we all indulge in as we navigate our way through daily life? I think I'm after someone to help unpack this one a little bit.
The coarser or more general context:
It's about not being attached to symbolic rites and rituals or taking them to be literally true.
For e.g. from SN 7.21:

The Buddha said to Sangarava:
“Is it really true, brahmin, that you practice purification by water,
believing in purification by water; that you live committed to the
practice of immersing yourself in water at dawn and dusk?”
“Yes, Master Gotama.”
“But brahmin, for what reason do you practice purification by water?”
“It’s because, Master Gotama, whatever bad deeds I’ve done during the
day I wash off by bathing at dusk; and whatever bad deeds I’ve done
during the night, I wash off by bathing at dawn. That’s the reason why
I practice purification by water.”

“The teaching is a lake with shores of ethics, brahmin,
unclouded, praised by the fine to the good.
There the knowledge-masters go to bathe,
and cross to the far shore without getting wet.”

When he had spoken, Saṅgārava said to the Buddha:
“Excellent, Master Gotama! Excellent! … From this day forth, may
Master Gotama remember me as a lay follower who has gone for refuge
for life.”

The more refined context:
From AN 3.78:

“Take the case of someone who cultivates precepts and observances, a
lifestyle, and a spiritual path, taking this as the essence. If
unskillful qualities grow while skillful qualities decline, that’s not
fruitful. However, if unskillful qualities decline while skillful
qualities grow, that is fruitful.”

From MN 24:

“Is the spiritual life lived under the Buddha for the sake of
purification of ethics?”
“Certainly not.”  ....
“In the same way, reverend, purification of ethics is only for the
sake of purification of mind. Purification of mind is only for the
sake of purification of view. Purification of view is only for the
sake of purification through overcoming doubt. Purification through
overcoming doubt is only for the sake of purification of knowledge and
vision of the variety of paths. Purification of knowledge and vision
of the variety of paths is only for the sake of purification of
knowledge and vision of the practice. Purification of knowledge and
vision of the practice is only for the sake of purification of
knowledge and vision. Purification of knowledge and vision is only for
the sake of extinguishment by not grasping. The spiritual life is
lived under the Buddha for the sake of extinguishment by not
grasping.”

From DN 16:

If it wishes, after my passing the Saṅgha may abolish the lesser and
minor training rules.

The purpose of precepts and observances, purification of ethics, and a spiritual path is only for the purification of the mind and cultivation of skillful qualities.
But being too attached to minor rules and rituals to the point that breaking them causes remorse and mental anguish, is unskillful and pollutes the mind.
It is enough to practise purification of ethics with the understanding that it is for the purification of the mind, and not be too attached to following minor rules and rituals to the letter.