Endlessly have a North American smoke (6)
I believe the answer is:
havana
'smoke' is the definition.
(I've seen this before)
'endlessly have a north american' is the wordplay.
'endlessly' means to remove the last letter.
'north american' becomes 'na'.
'have' with its final letter taken off is 'hav'.
'hav'+'a'+'na'='HAVANA'
(Other definitions for havana that I've seen before include "Cuba's capital" , "Cuban capital - cigar" , "Smoke" , "Caribbean capital" , "city" .)