Bill producing problem around back of restaurant (6)
I believe the answer is:
poster
'bill' is the definition.
('poster' can be a synonym of 'bill')
'problem around back of restaurant' is the wordplay.
'problem' becomes 'poser' (poser is a kind of problem).
'around' means one lot of letters goes inside another.
'back of restaurant' becomes 't' (I can't explain this - if you can you should give a lot more credence to this answer).
'poser' going around 't' is 'POSTER'.
'producing' acts as a link.
Can you help me to learn more?
(Other definitions for poster that I've seen before include "Town near Glasgow" , "Large advert" , "Largfe public notice." , "Paper advertisement for topers" , "Person who sends" .)