Catch half-decent fish (8)
I believe the answer is:
entangle
'catch' is the definition.
(I've seen this before)
'half-decent fish' is the wordplay.
'half' indicates taking half.
'fish' becomes 'angle' (angling is a kind of fishing**).
'decent' with half the letters taken is 'ent'.
'ent'+'angle'='ENTANGLE'
(Other definitions for entangle that I've seen before include "Involve undesirably" , "snarl" , "Create confusion" , "Get all twisted up" , "Confuse" .)