Intelligence issue that’s pretty dull? (4,6)
I believe the answer is:
grey matter
'intelligence' is the definition.
(I've seen this before)
'issue that's pretty dull?' is the wordplay.
I cannot quite understand how this works, but
'issue' could be 'matter' (synonyms) and 'matter' is located in the answer.
'dull?' could be 'grey' (I've seen this before) and 'grey' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for grey matter that I've seen before include "intellectual capacity?" , "Intelligence; the brain" , "Brain tissue" , "stuff in the head" , "Issue lacking clear boundaries" .)