He’s stupid, taking the north-east road (4)
I believe the answer is:
nerd
'he's stupid' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'the north-east road' is the wordplay.
'the north east' becomes 'ne'.
'road' becomes 'rd' (abbreviation).
'ne'+'rd'='NERD'
'taking' acts as a link.
Can you help me to learn more?
(Other definitions for nerd that I've seen before include "Boring, trivia-obsessed type" , "Anorak (informal)" , "one that's overly cerebral" , "Geek, anorak (sl.)" , "Student who is ridiculed for studying excessively" .)