A composition of spilled soup (4)
I believe the answer is:
opus
'a composition' is the definition.
(I know that opus can be written as opus)
'spilled soup' is the wordplay.
'spilled' indicates an anagram.
'soup' is an anagram of 'OPUS'.
'of' is the link.
(Other definitions for opus that I've seen before include "Major work" , "Composer's catalogue number" , "A Latin work" , "Creative work, eg in writing, art or music" , "Work or composition, usually musical" .)