Catch in one trap (3)
I believe the answer is:
net
'catch' is the definition.
(net can mean to catch)
'in one trap' is the wordplay.
'in' indicates a hidden word.
'NET' is hidden within 'one trap'.
(Other definitions for net that I've seen before include "device to divide the court" , "Lattice" , "Fish-catching mesh" , "Overall; mesh" , "Clear profit or gain" .)