Measure of intelligence, say, not quite sorted out (8)
I believe the answer is:
quotient
'measure of intelligence' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe there's an association between them I don't understand?
'not quite sorted out' is the wordplay.
'sorted out' is an anagram indicator.
'not'+'quite'='notquite'
'notquite' is an anagram of 'QUOTIENT'.
'say' is the link.
Can you help me to learn more?
(Other definitions for quotient that I've seen before include "In maths, it's obtained by dividing one quantity by another" , "Result of division sum" , "Result of division (maths)" , "Not quite (anag) - ratio" , "The Q in IQ" .)