Singer's party food's going round (7)
I believe the answer is:
madonna
'singer's' is the definition.
(American singer)
'party food's going round' is the wordplay.
'party' becomes 'do' (do can informally mean a party).
'food' becomes 'manna' (manna is a kind of food).
'going round' indicates putting letters inside (some letters go around others).
'do' inserted into 'manna' is 'MADONNA'.
(Other definitions for madonna that I've seen before include "Religious art subject - pop singer, b. 1958" , "Mother figure" , "Virgin Mary - or American showbiz queen" , "Like a Virgin singer" , "pop star" .)