Supplier of escort to follow prince (6)
I believe the answer is:
pusher
'supplier' is the definition.
(push can mean to sell or supply)
'escort to follow prince' is the wordplay.
'escort' becomes 'usher' (usher is a kind of escort).
'to follow' says to put letters next to each other (some letters go after or follow others).
'prince' becomes 'p' (abbreviation).
'usher' after 'p' is 'PUSHER'.
'of' is the link.
(Other definitions for pusher that I've seen before include "See 20" , "Criminal who sells illegal drugs" , "Street seller of illegal drugs" , "A seller of drugs on the streets" .)