Some cousin a tradesman, Frank? (7)
I believe the answer is:
sinatra
'frank?' is the definition.
(I've seen this before)
'some cousin a tradesman' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'SINATRA' is hidden within 'cousin a tradesman'.
(Other definitions for sinatra that I've seen before include "Francis Albert, mourned singer" , "Francis Albert did it his way" , "Old singer" , "Francis Albert, late lamented singer" , "'Old Blue Eyes'" .)