Selling last of ale and port in bar, ... (6)
I believe the answer is:
retail
'selling last of ale' is the definition.
'retail' can be an answer for 'selling' (thesaurus). I'm not certain of the 'last of ale' bit.
'port in bar' is the wordplay.
'port' becomes 'et' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'bar' becomes 'rail' (rail is a kind of bar).
'et' put inside 'rail' is 'RETAIL'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for retail that I've seen before include "Form of sales" , "Sale of goods to customers" , "sort of sale" , "Sell in small quantities" , "Sell; pass on (e.g. gossip)" .)