Expression in America for end of the line (8)
I believe the answer is:
terminus
'end of the line' is the definition.
(I've seen this before)
'expression in america' is the wordplay.
'expression' becomes 'term' (I've seen this before).
'america' becomes 'us' (abbreviation for the United States).
'term'+'in'+'us'='TERMINUS'
'for' is the link.
(Other definitions for terminus that I've seen before include "End - objective" , "End (of rail line)" , "Limit" , "End, extremity" , "final point" .)