Perhaps cowboy managed singer (7)
I believe the answer is:
rancher
'perhaps cowboy' is the definition.
(I know that cowboy is a type of rancher)
'managed singer' is the wordplay.
'managed' becomes 'ran' (both can mean organised or was in charge of).
'singer' becomes 'cher' (American singer).
'ran'+'cher'='RANCHER'
(Other definitions for rancher that I've seen before include "Cattle farmer in the Americas" , "Cattleman" , "Cattle baron" , "North American cattle farmer" , "Hacienda owner" .)