Young man's brought in special service dishes (6)
I believe the answer is:
salads
'dishes' is the definition.
(salad is a kind of dish)
'young man's brought in special service' is the wordplay.
'young man' becomes 'lad' (lad can mean a boy or young man).
'brought in' indicates putting letters inside.
'special service' becomes 'SAS' (Special Air Service).
'lad' placed into 'sas' is 'SALADS'.
(Other definitions for salads that I've seen before include "Cold dishes with lettuce etc" , "Cold meals based on lettuce and vegetables" , "Food mixtures including greens" , "Fruit or vegetable dishes" , "Cold, dressed dishes" .)