Meal without starter is a stimulant (5)
I believe the answer is:
upper
'stimulant' is the definition.
(I know that upper is a type of stimulant)
'meal without starter' is the wordplay.
'meal' becomes 'supper' (supper is a kind of meal).
'without starter' means to remove the first letter.
'supper' with its initial letter removed is 'UPPER'.
'is a' acts as a link.
(Other definitions for upper that I've seen before include "Higher; part of shoe" , "Higher; superior" , "Part of a shoe; drug" , "Higher; part of boot" , "Section of Oxford" .)