Enlists searcher exposed over offence (5,2)
I believe the answer is:
ropes in
'enlists' is the definition.
'searcher exposed over offence' is the wordplay.
'searcher' becomes 'groper' (someone groping around to find something).
'exposed' means to look at the middle letters (outside letters removed).
'over' says to put letters next to each other.
'offence' becomes 'sin' (I've seen this before).
The centre of 'groper' is 'rope'.
'rope'+'sin'='ROPES IN'
(Other definitions for ropes in that I've seen before include "Recruits" , "Gets involved" , "Involves" .)