Oriental festival ending in altercation (7)
I believe the answer is:
eastern
'oriental' is the definition.
(synonyms)
'festival ending in altercation' is the wordplay.
'festival' becomes 'easter' (Christian festival).
'ending in' indicates one should take the final letters.
The last letter of 'altercation' is 'n'.
'easter'+'n'='EASTERN'
(Other definitions for eastern that I've seen before include "Earnest (anag.)" , "Asian" , "in Beijing, possibly" , "towards daybreak?" , "Could be Chinese" .)