Criticism of salad ingredient (6)
I believe the answer is:
rocket
I believe this clue is a double definition.
'criticism' is the first definition.
(I have seen 'Severe criticism' mean 'rocket' so perhaps 'criticism' could also mean 'rocket')
'salad ingredient' is the second definition.
(I've seen this before)
'of' acts as a link.
(Other definitions for rocket that I've seen before include "Projectile salad ingredient" , "Projectile lettuce" , "Roasting" , "Structure that flies by expelling gases - or a reprimand" , "Projectile firework" .)