Put back controls on London gallery (9)
I believe the answer is:
reinstate
'put back' is the definition.
(to reinstate is to return or restore)
'controls on london gallery' is the wordplay.
'controls' becomes 'reins' (take the reins).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'london gallery' becomes 'tate' (I've seen this in another clue).
'reins'+'tate'='REINSTATE'
(Other definitions for reinstate that I've seen before include "Restore to former post" , "Restore, put back" , "Bring back" , "Put back into office" , "Put back in position" .)