Work to locate resistance (10)
I believe the answer is:
opposition
'resistance' is the definition.
('opposition' can be a synonym of 'resistance')
'work to locate' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'to locate' becomes 'position' (I've seen this before).
'op'+'position'='OPPOSITION'
(Other definitions for opposition that I've seen before include "those out of power" , "obstruction" , "antagonism" , "Political party" , "Rivalry" .)