Dealers starred in play (7)
I believe the answer is:
traders
'dealers' is the definition.
('trader' can be a synonym of 'dealer')
'starred in play' is the wordplay.
'in play' indicates an anagram (letters play around).
'starred' is an anagram of 'TRADERS'.
(Other definitions for traders that I've seen before include "businessmen" , "Dealers" , "Sellers" .)