Avoid American wife (6)
I believe the answer is:
missus
'wife' is the definition.
(someone's missus is their wife)
'avoid american' is the wordplay.
'avoid' becomes 'miss' (miss can mean to avoid).
'american' becomes 'US' (United States).
'miss'+'us'='MISSUS'
(Other definitions for missus that I've seen before include "The old lady" , "Dutch American" , "As partner" , "Wife (informal)" , "Wife (colloquial)" .)