Scot, or a no-good American? (5)
I believe the answer is:
angus
'scot' is the definition.
(I've seen this before)
'a no-good american?' is the wordplay.
'no good' becomes 'ng' (abbreviation).
'american?' becomes 'us' (abbreviation for United States).
'a'+'ng'+'us'='ANGUS'
'or' is the link.
(Other definitions for angus that I've seen before include "Scotsman" , "Scottish cattle area" , "Lamb of God - . . . Dei" , "Former Scottish county" , "Steer" .)