Impresario who’s trained crew (7)
I believe the answer is:
showman
'impresario' is the definition.
(synonyms)
'who's trained crew' is the wordplay.
'trained' is an anagram indicator (to train can mean to grow something into a shape).
'crew' becomes 'man' (both can mean to operate or staff).
'whos' anagrammed gives 'show'.
'show'+'man'='SHOWMAN'
(Other definitions for showman that I've seen before include "Impresario" , "Circus or fair manager" , "Circus proprietor" , "Person helping to present" , "Entertainer" .)