Dull-witted but more than right (6)
I believe the answer is:
obtuse
This clue is a double definition.
'dull-witted' is the first definition.
(I've seen this before)
'more than right' is the second definition.
(I've seen this before)
'but' is the link.
(Other definitions for obtuse that I've seen before include "A stupid angle?" , "Exaggerate" , "angle, perhaps" , "Blunt, dull-witted" , "Dull or blunt" .)