Name popular American destination (8)
I believe the answer is:
terminus
'destination' is the definition.
('terminus' can be a synonym of 'destination')
'name popular american' is the wordplay.
'name' becomes 'term' (I've seen this in other clues).
'popular' becomes 'in'.
'american' becomes 'us'.
'term'+'in'+'us'='TERMINUS'
(Other definitions for terminus that I've seen before include "End of the line for tram or bus" , "End station" , "Destination point" , "Final station on bus route" , "End of bus/rail route" .)