Salad ingredient Diana spots outside (6)
I believe the answer is:
radish
'salad ingredient' is the definition.
(radishes are often used in salads)
'diana spots outside' is the wordplay.
'diana' becomes 'Di' (Di is short for Diana).
'spots' becomes 'rash' (I've seen this before).
'outside' indicates putting letters inside.
'di' put inside 'rash' is 'RADISH'.
(Other definitions for radish that I've seen before include "Hottish salad plant" , "Bit of salad" , "Pungent, red salad vegetable" , "Small red salad vegetable" , "Plant with crisp root eaten raw" .)