One paying a flat fee for Takeaway with every starter coming with the ultimate cheese (6)
I believe the answer is:
lessee
'one paying a flat fee' is the definition.
(I've seen this in another clue)
'takeaway with every starter coming with the ultimate cheese' is the wordplay.
'takeaway' becomes 'less' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'starter' suggests taking the first letters.
'coming with' is a charade indicator (letters next to each other).
'the ultimate' suggests the final letters.
The first letter of 'every' is 'e'.
The final letter of 'cheese' is 'e'.
'less'+'e'+'e'='LESSEE'
'for' is the link.
(Other definitions for lessee that I've seen before include "Who pays the rent" , "One who rents" , "Hirer of property" , "Person who rents" , "The one taking out lease" .)