Orca, able to destroy fish (8)
I believe the answer is:
albacore
'fish' is the definition.
(albacore is a kind of fish)
'orca able to destroy' is the wordplay.
'to destroy' is an anagram indicator (I've seen 'destroyed' mean this).
'orca'+'able'='orcaable'
'orcaable' is an anagram of 'ALBACORE'.
(Other definitions for albacore that I've seen before include "Large tuna; able orca (anag.)" , "fish" , "Long-fin tunny" , "Variety of tuna" .)