Remaining witnesses heard abroad (8)
I believe the answer is:
overseas
'abroad' is the definition.
(both can mean in another country)
'remaining witnesses heard' is the wordplay.
'remaining' becomes 'over' (as in 'we ate them all but had one over').
'witnesses' becomes 'sees' ('see' can be a synonym of 'witness').
'heard' shows a homophone (sound like).
'sees' is a homophone of 'seas'.
'over'+'seas'='OVERSEAS'
(Other definitions for overseas that I've seen before include "In a foreign country" , "abroad - with 12a" , "In foreign parts" , "Exotic" .)