Quick to communicate (7)
I believe the answer is:
express
I believe this is a double definition.
'quick' is the first definition.
(thesaurus)
'communicate' is the second definition.
(expressing is a kind of communicating)
'to' is the link.
(Other definitions for express that I've seen before include "Convey; high-speed" , "for a specific purpose?" , "haste" , "Fast train; specific" , "Quickly" .)