Salad ingredient Di spots outside (6)
I believe the answer is:
radish
'salad ingredient' is the definition.
(radishes are often used in salads)
'di spots outside' is the wordplay.
'spots' becomes 'rash' (as in skin irritation).
'outside' is an insertion indicator (some letters go outside others).
'di' going within 'rash' is 'RADISH'.
(Other definitions for radish that I've seen before include "Bit of salad" , "Hard vegetable" , "Pungent, red salad vegetable" , "Sir had this vegetable" , "Hottish salad plant" .)