Court dunderhead in the trees (4)
I believe the answer is:
wood
'trees' is the definition.
'court dunderhead' is the wordplay.
'court' becomes 'woo' (both can mean to romance someone).
'dunderhead' becomes 'd' (head letter of 'dunder').
'woo'+'d'='WOOD'
'in the' is the link.
(Other definitions for wood that I've seen before include "Cooing bird" , "Concert promoter" , "What you might need to play golf" , "Material from trees" , "Wind instrument - golf club" .)