Is no trouble suppressing demand for vegetable (8)
I believe the answer is:
scallion
'for vegetable' is the definition.
(scallion is a kind of vegetable)
'is no trouble suppressing demand' is the wordplay.
'trouble' is an anagram indicator.
'suppressing' means one lot of letters goes inside another.
'demand' becomes 'call' (call is a kind of demand).
'is'+'no'='isno'
'isno' anagrammed gives 'sion'.
'sion' placed around 'call' is 'SCALLION'.
(Other definitions for scallion that I've seen before include "Vegetable" , "Green onion" , "sort of onion" , "A spring onion with long neck" , "Spring 12" .)