Food like a lobster back in soup (7)
I believe the answer is:
chowder
'soup' is the definition.
(I know that Chowder is a soup)
'food like a lobster back' is the wordplay.
'food' becomes 'chow' (chow can informally mean food).
'like a lobster' becomes 'red' (I've seen this in another clue).
'back' is a reversal indicator.
'red' written backwards gives 'der'.
'chow'+'der'='CHOWDER'
'in' is the link.
(Other definitions for chowder that I've seen before include "Clam stew, soup" , "clammy" , "Rich seafood soup" , "dish in America" , "possible first course?" .)