Return afterwards, holding one to sell (6)
I believe the answer is:
retail
'sell' is the definition.
(I know that retail is a more specific form of the action sell)
'return afterwards holding one' is the wordplay.
'return' says the letters should be written backwards.
'afterwards' becomes 'later' (synonyms).
'holding' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'later' placed around 'i' is 'liater'.
'liater' reversed gives 'RETAIL'.
'to' is the link.
(Other definitions for retail that I've seen before include "Form of sales" , "Sell - supply account" , "I alter for trade that sells to public" , "The sale of goods to the public" , "Sell in small quantities" .)