Guy with girlfriend's approval (7)
I believe the answer is:
mandate
'approval' is the definition.
(I've seen this before)
'guy with girlfriend's' is the wordplay.
'guy' becomes 'man' (I've seen this before).
'with' says to put letters next to each other.
'girlfriend' becomes 'date' (I've seen this in other clues).
'man'+'date'='MANDATE'
(Other definitions for mandate that I've seen before include "Authority conferred on a tandem" , "Make compulsory" , "Give authority to" , "Legal authorisation" , "Decree" .)