Is one intelligent and good-natured? (7)
I believe the answer is:
amiable
'good-natured?' is the definition.
('amiable' can be similar in meaning to 'good-natured')
'is one intelligent' is the wordplay.
'is one' becomes 'ami' ('Is one?' could humorously mean 'Am I?').
'intelligent' becomes 'able'.
'ami'+'able'='AMIABLE'
'and' acts as a link.
(Other definitions for amiable that I've seen before include "Charming" , "Lovable, friendly" , "'Cordial, friendly (7)'" , "'Affable, genial (7)'" , "'Friendly, pleasant and good-tempered (7)'" .)