Gunners fiddle short course (7)
I believe the answer is:
ravioli
'course' is the definition.
(I've seen this before)
'gunners fiddle short' is the wordplay.
'gunners' becomes 'ra' (Royal Artillery).
'fiddle' becomes 'violin' (synonyms).
'short' means to remove the last letter.
'violin' with its last letter removed is 'violi'.
'ra'+'violi'='RAVIOLI'
(Other definitions for ravioli that I've seen before include "Pasta resembling pillowcases" , "Stuffed pasta squares" , "you might have at La Scala?" , "Meat-filled pasta squares" , "created with Italian gut in mind" .)