Words showing intelligence — any number thrown in (5)
I believe the answer is:
nouns
'words' is the definition.
(noun is a kind of word)
'intelligence any number thrown in' is the wordplay.
'intelligence' becomes 'nous' (I've seen this in other clues).
'any number' becomes 'n' (mathematical symbol for an unspecified number).
'thrown in' is an insertion indicator.
'nous' going around 'n' is 'NOUNS'.
'showing' acts as a link.
(Other definitions for nouns that I've seen before include "They refer to people, places and things" , "Substantives" , "Words referring to people, places or things" , "Words referring to person, place or thing" , "Naming words" .)