Do for retiring salesman taking shape (7)
I believe the answer is:
perform
'do' is the definition.
('perform' can be a synonym of 'do')
'retiring salesman taking shape' is the wordplay.
'retiring' shows that the letters should be reversed in order.
'salesman' becomes 'rep' (I've seen this before).
'taking' means one lot of letters go next to another.
'shape' becomes 'form' ('form' can be a synonym of 'shape').
'rep' reversed gives 'per'.
'per'+'form'='PERFORM'
'for' acts as a link.
(Other definitions for perform that I've seen before include "Act - accomplish" , "seen to make a profit?" , "Carry out (duties)" , "Carry out (action)" , "act on stage" .)