Tatum, perhaps, works as an expert craftsman (7)
I believe the answer is:
artisan
'expert craftsman' is the definition.
(an artisan is a skilled craftsperson)
'tatum perhaps works as an' is the wordplay.
'tatum perhaps' becomes 'Art' (jazz pianist Art Tatum).
'works as' becomes 'is' (eg someone who works as a postman is a postman).
'art'+'is'+'an'='ARTISAN'
(Other definitions for artisan that I've seen before include "Tsarina (anag.)" , "Skilled worker at craft or trade" , "craftsman of his trade" , "Crafty sort" , "Handy worker" .)