I have gtf file containing 7 columns from which i am going extract only gene name part from column 7th.

The 7th column contains some information including `gene_id`, `gene_name` and so on that I posted one row of column 7th below:

    gene_id "XLOC_000001"; transcript_id "TCONS_00000001"; exon_number "1"; gene_name "NAC001"; oId "AT1G01010.1"; nearest_ref "AT1G01010.1"; class_code "="; tss_id

I need only `gene_name` from this column, for example "NAC001", how can I extract which I need please?
Sorry I missed the part that you only posted column 7 from your file. Either use @dschika's solution below or cut the 7th column and then use the one liner below.

    $ awk -F ";" '{sub(/gene_name/,""); print $4}' your_file

If you don't need the quotes around the gene name

    $ awk -F ";" '{sub(/gene_name/,""); print $4}' your_file | sed 's/"//g'