No trap for fish (6)
I believe the answer is:
tarpon
'for fish' is the definition.
(tarpon is a kind of fish)
'no trap' is the wordplay.
'no trap' can be anagrammed to 'TARPON'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for tarpon that I've seen before include "Large silvery game fish of coastal waters off Florida" , "No part for this large fish" , "Great fish of Florida" .)