Could be a strain becoming a workman! (7)
I believe the answer is:
artisan
'a workman' is the definition.
(I have seen 'Skilled workman' mean 'artisan' so perhaps 'workman' could also mean 'artisan')
'could be a strain' is the wordplay.
'could be' indicates an anagram.
'a'+'strain'='astrain'
'astrain' with letters rearranged gives 'ARTISAN'.
'becoming' is the link.
(Other definitions for artisan that I've seen before include "Tsarina (anag.)" , "craftsman of his trade" , "crafty person?" , "Skilled manual 17" , "Skilled craftsperson" .)