Criticise the right cat (7)
I believe the answer is:
'cat' is the definition.
(I know that Panther is a cat)
'criticise the right' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'right' becomes 'r' (common abbreviation).
(Other definitions for panther that I've seen before include "animal!" , "Big cat" , "Bagheera?" , "See 2" , "Then rap the large black cat" .)