Sailor on route to foreign parts (6)
I believe the answer is:
abroad
'to foreign parts' is the definition.
(as in going abroad)
'sailor on route' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'route' becomes 'road' (synonyms).
'ab'+'road'='ABROAD'
(Other definitions for abroad that I've seen before include "Stare lecherously at (someone)" , "over a wide area" , "not in Britain" , "At large - overseas" , "on the Continent" .)