Bung a bit of bacon in soft cheese (5)
I believe the answer is:
bribe
'bung' is the definition.
(bung can mean a bribe)
'a bit of bacon in soft cheese' is the wordplay.
'a bit of' says to take the initial letters.
'in' means one lot of letters goes inside another.
'soft cheese' becomes 'brie' (brie is a soft cheese).
The first letter of 'bacon' is 'b'.
'b' placed inside 'brie' is 'BRIBE'.
(Other definitions for bribe that I've seen before include "Sweetener, inducement" , "Illegal incentive" , "Oil the palm (of)" , "Illegal payment in exchange for favour" , "Illegal inducement" .)