Greek boy seen after no-one goes west (6)
I believe the answer is:
ionian
'greek' is the definition.
(I know that Ionian is a type of greek)
'boy seen after no-one goes west' is the wordplay.
'boy' becomes 'ian' (man's name).
'seen after' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'goes west' is an anagram indicator (to go west can mean to run into trouble).
'no'+'i'='noi'
'noi' anagrammed gives 'ion'.
'ian' put after 'ion' is 'IONIAN'.
(Other definitions for ionian that I've seen before include "from Greek Islands" , "Sea between Greece and Sicily" , "Sea between southern Italy and western Greece" , "Sea between Greece and south Italy" .)