Insect on soft cheese for a short time (7)
I believe the answer is:
briefly
'for a short time' is the definition.
('briefly' can be a synonym of 'for a short time')
'insect on soft cheese' is the wordplay.
'insect' becomes 'fly' (fly is a kind of insect).
'on' is a charade indicator (letters next to each other).
'soft cheese' becomes 'brie' (I've seen this before).
'fly' after 'brie' is 'BRIEFLY'.
(Other definitions for briefly that I've seen before include "Cursorily" , "Fleetingly" , "gets to the point" , "In a nutshell" , "In a few words" .)