Friendly but stupid? (5)
I believe the answer is:
thick
I believe this is a double definition.
'friendly' is the first definition.
(I've seen this before)
'stupid?' is the second definition.
('thick' can be similar in meaning to 'stupid')
'but' acts as a link.
(Other definitions for thick that I've seen before include "deficient in understanding" , "having such a head?" , "Stupid; close-packed" , "Wide -- impenetrable" , "Wide, broad" .)