what were the causes which led to this clash?
To remove the Japanese control over the region.
Offensive against the Japanese supply system
 During the Battle of Sattelberg, the Allies set out to cut this supply line. A three-pronged approach was taken:

By December, the pitiful condition of Japanese prisoners confirmed for the Australians that "the Japanese logistic system was in the final stages of breakdown". 
in which country did the battle of sio take place? Papua New Guinea. on what date did this fight begin? December 1943. whom was it fought between? Australian and Papuan forces , and the Japanese.
UNANSWERABLE UNANSWERABLE Because Japanese did not leave the area.
Battle of Sio
Background
Although beaten, the Japanese did not leave the area. Lieutenant General Shigeru Katagiri, the commander of the Japanese 20th Division, ordered the 80th Infantry Regiment to hold the Wareo area to protect the withdrawal of the 79th Infantry Regiment and other units. The 2nd Battalion, 238th Infantry Regiment was to act as a rearguard on the coast. Lieutenant General Frank Berryman, the commander of Australian II Corps, now urged Wootten to commence a coastal advance to cut the Japanese supply lines and force Adachi to retreat from the Huon Peninsula if he were not already doing so. Wootten took a more cautious approach. The Battle of Wareo proved that the Japanese intended to defend the area.
wiki:8723403
Battle of Sio [SEP] Offensive against the Japanese supply system
The same night, two barges were also sunk north of Sio Island. When General Berryman saw Vice Admiral Thomas C. Kinkaid, the commander of the Allied Naval Forces, on 14 December, he made a point of congratulating him on the work his PT boats were doing. Lieutenant General Tsutomu Yoshihara, Chief of Staff of the Japanese Eighteenth Army recalled: