Cashless trade in British art never ends (6)
I believe the answer is:
barter
'cashless trade' is the definition.
(I've seen this in another clue)
'in british art never ends' is the wordplay.
'in' means one lot of letters goes inside another.
'british' becomes 'br' (abbreviation for British).
'never ends' becomes 'e' (I am not sure about this - if you are sure you should believe this answer much more).
'art'+'e'='arte'
'br' placed around 'arte' is 'BARTER'.
Can you help me to learn more?
(Other definitions for barter that I've seen before include "Exchange goods without using money" , "Trade not involving money" , "Trade by direct exchange of goods" , "Trade or swap" , "Give (goods) in exchange" .)