Friendly, am I? — Vince (8)
I believe the answer is:
amicable
'friendly' is the definition.
('amicable' is associated in meaning with 'friendly')
'am i? vince' is the wordplay.
'vince' becomes 'cable' (Sir Vince Cable).
'am'+'i'+'cable'='AMICABLE'
(Other definitions for amicable that I've seen before include "Friendly, nonthreatening" , "warm" , "Friendly, good-humoured" , "friendliness" , "Friendly and sociable" .)