Unscrupulous tradesman browbeat youngster (6)
I believe the answer is:
cowboy
'unscrupulous tradesman' is the definition.
(informal term for an unqualified tradesman)
'browbeat youngster' is the wordplay.
'browbeat' becomes 'cow' (I've seen this before).
'youngster' becomes 'boy'.
'cow'+'boy'='COWBOY'
(Other definitions for cowboy that I've seen before include "Wrangler" , "Wild West character" , "Sort of builder" , "(Gun-toting?) untrustworthy workman" , "Mounted herdsman" .)