Little inclination to conceal intelligence, a smart alec (4-2-3)
I believe the answer is:
know-it-all
'smart alec' is the definition.
(I've seen this before)
'little inclination to conceal intelligence a' is the wordplay.
'little inclination' becomes 'knoll'.
'to conceal' is an insertion indicator.
'intelligence' becomes 'wit' (wit is a kind of intelligence).
'wit'+'a'='wita'
'knoll' enclosing 'wita' is 'KNOW-IT-ALL'.
(Other definitions for know-it-all that I've seen before include "Unteachable bigot" , "Smart alec" .)