Quick to convey (7)
I believe the answer is:
express
This clue is a double definition.
'quick' is the first definition.
(I've seen this before)
'convey' is the second definition.
(expressing is a kind of conveying)
'to' is the link.
(Other definitions for express that I've seen before include "Quick -- exact" , "Fleet" , "Put into words - fast" , "clear > couch" , "Of train, travelling rapidly with few or no stops" .)