Exchange involving pub worker, no end (6)
I believe the answer is:
barter
'exchange' is the definition.
(barter is a kind of exchange)
'pub worker no end' is the wordplay.
'pub worker' becomes 'bartender' (I've seen this before).
'no' suggests deleting specific letters.
'bartender' with 'end' taken out is 'BARTER'.
'involving' acts as a link.
(Other definitions for barter that I've seen before include "Trade by direct exchange of goods" , "Trade without using money" , "Exchange, bargain" , "Exchange goods without using money" , "Trade not involving money" .)