He is or could be a shopkeeper (6)
I believe the answer is:
hosier
'a shopkeeper' is the definition.
(I know that hosier is a type of shopkeeper)
'he is or could be' is the wordplay.
'could be' is an anagram indicator.
'he'+'is'+'or'='heisor'
'heisor' with letters rearranged gives 'HOSIER'.
(Other definitions for hosier that I've seen before include "tight merchant" , "Seller of stockings etc" , "Dealer in socks and stockings" , "Maker or dealer in stockings" , "seller of 24 [NYLONS]" .)