Ape-lord fighting powerful cat (7)
I believe the answer is:
leopard
'powerful cat' is the definition.
(I've seen this before)
'ape-lord fighting' is the wordplay.
'fighting' is an anagram indicator (I've seen this in other clues).
'ape'+'lord'='apelord'
'apelord' anagrammed gives 'LEOPARD'.
(Other definitions for leopard that I've seen before include "Powerful cat" , "Panther" , "Animal that doesn't change its spots" , "Spotted feline" , "Big cat with spots" .)