Night on the town in becoming uniform (7,3)
I believe the answer is:
evening out
This clue is a double definition.
'night on the town' is the first definition.
'becoming uniform' is the second definition.
(to 'even out' can mean to become regular)
'in' is the link.
(Other definitions for evening out that I've seen before include "Date" , "getting rid of inequalities" , "Trip to the theatre, perhaps" , "Making uniform" , "it's what Lilburne wanted" .)