Sell something with a bad tear for one pound (6)
I believe the answer is:
retail
'sell' is the definition.
(retailing is a kind of selling)
'bad tear for one pound' is the wordplay.
'bad' indicates an anagram.
'for' means one lot of letters go next to another (I've seen this in other clues).
'one' becomes 'I' (Roman numeral).
'pound' becomes 'l' ().
'tear' after 'i' is 'itear'.
'itear' is an anagram of 'retai'.
'retai'+'l'='RETAIL'
'something with a' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for retail that I've seen before include "Tell story" , "The trade serving the public" , "Direct sale to the consumer" , "This trade serves the general public" , "The selling of goods to consumers" .)