Radio DJ Simon’s condiment (4)
I believe the answer is:
mayo
'condiment' is the definition.
(I know that mayo is a type of condiment)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for mayo that I've seen before include "County of north-west Ireland" , "Thick creamy dressing" , "Cold, creamy sauce (abbr)" , "Salad dressing (informal)" , "County of Western Eire" .)