Concision; shortness (7)
I believe the answer is:
brevity
This clue is a double definition.
'concision' is the first definition.
(I've seen this before)
'shortness' is the second definition.
(I've seen this in another clue)
(Other definitions for brevity that I've seen before include "The soul of wit?" , "Succinctness" , "economy ..." , "Terseness" , "considered the essence of wit" .)