Traveller a long way away in south at all times (8)
I believe the answer is:
seafarer
'traveller' is the definition.
(I've seen this before)
'a long way away in south at all times' is the wordplay.
'a long way away' becomes 'afar' (I've seen this in another clue).
'in' means one lot of letters goes inside another.
'south' becomes 's' (abbreviation).
'at all times' becomes 'eer' (archaic or poetic word meaning ever or forever).
's'+'eer'='seer'
'afar' inserted into 'seer' is 'SEAFARER'.
(Other definitions for seafarer that I've seen before include "A traveller on the ocean, like sailor" , "Salt" , "One going by ship" , "Marine traveller" , "Traveller by ship" .)