Sell again at the end (6)
I believe the answer is:
retail
'sell' is the definition.
(retailing is a kind of selling)
'again at the end' is the wordplay.
'again' becomes 're' (prefix meaning 'again').
'at' says to put letters next to each other.
'the end' becomes 'tail' (tail is a kind of end).
're'+'tail'='RETAIL'
(Other definitions for retail that I've seen before include "Sell; pass on (e.g. gossip)" , "This trade sells to the general public" , "report" , "Trade selling goods to the general public" , "Tell story" .)