Two-way traffic, no cash needed (6)
I believe the answer is:
barter
'two-way traffic' is the definition.
'barter' can be an answer for 'traffic' (thesaurus). I am unsure of the 'two-way' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for barter that I've seen before include "Trade by exchanging commodities" , "Trade not involving money" , "Trade without using money" , "Trade or swap" , "Exchange goods without using money" .)