Continental character, and when he might turn up? (3)
I believe the answer is:
eta
I believe this clue is a double definition.
'continental character' is the first definition.
(letter of the Greek alphabet)
'when he might turn up?' is the second definition.
(ETA is short for estimated time of arrival)
'and' is the link.
(Other definitions for eta that I've seen before include "Greek letter - Basque nationalist movement" , "When one is due" , "Foreign letter" , "giving expected termination of journey" , "Greek letter E; estimated time of arrival (abbr.)" .)