Firm returning in former place (6)
I believe the answer is:
locate
'place' is the definition.
('locate' can be a synonym of 'place')
'firm returning in former' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'returning' shows that the letters should be reversed in order.
'in' indicates putting letters inside.
'former' becomes 'late'.
'co' reversed gives 'oc'.
'oc' going into 'late' is 'LOCATE'.
(Other definitions for locate that I've seen before include "Discover place where thing is" , "Lay one's hands on (something)" , "Pinpoint in Alecto" , "spot" , "Track down" .)