Catch in fine trap (3)
I believe the answer is:
'catch' is the definition.
(net can mean to catch)
'in fine trap' is the wordplay.
'in' indicates a hidden word.
'NET' can be found hidden inside 'fine trap'.
(Other definitions for net that I've seen before include "Amount remaining after deductions" , "Trap; open-weave fabric" , "Mesh; after tax" , "Clear profit or gain" , "Mesh or web" .)