Give publicity to letters - it's a quick means of communication (7)
I believe the answer is:
airmail
'communication' is the definition.
(I know that airmail is a type of mail)
'give publicity to letters' is the wordplay.
'give' says to put letters next to each other.
'publicity' becomes 'air' (I've seen this in other clues).
'to letters' becomes 'mail' (I've seen this before).
'air' put next to 'mail' is 'AIRMAIL'.
'it's a quick means of' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for airmail that I've seen before include "I'm a liar (anag)" , "communication" , "It's marked "par avion"" , "Way of communicating" , "Letters sent up" .)