First course perhaps is very revolting (4)
I believe the answer is:
soup
'first course' is the definition.
(I've seen this before)
'is very revolting' is the wordplay.
'is very' becomes 'so' (both can mean 'extremely').
'revolting' becomes 'up' (rising up or revolting).
'so'+'up'='SOUP'
'perhaps' acts as a link.
(Other definitions for soup that I've seen before include "Opus (anag) - typical starter" , "Eg, potage, broth" , "Eg, mulligatawny" , "Eskimo people" , "Liquid dish" .)