Vegetable initially served before sweet (4)
I believe the answer is:
spud
'vegetable' is the definition.
(spud is a kind of vegetable)
'initially served before sweet' is the wordplay.
'initially' says to take the initial letters.
'before' is a charade indicator (letters next to each other).
'sweet' becomes 'pud' (pud is a kind of sweet**).
The first letter of 'served' is 's'.
's'+'pud'='SPUD'
(Other definitions for spud that I've seen before include "The common potato" , "Tater" , "King Edward, e.g." , "One could be in jacket" , "One might have an eye" .)