List of prime numbers (4)
I believe the answer is:
'list' is the definition.
(list of dishes)
'of prime numbers' is the wordplay.
'of' indicates the answer is hidden within the clue.
'MENU' can be found hidden inside 'prime numbers'.
(Other definitions for menu that I've seen before include "List of items to choose from as in restaurant" , "Options available" , "List of dishes on offer" , "List of items available in restaurant (4)" , "restaurant guide" .)