Witch in ancient Carthage (3)
I believe the answer is:
hag
'witch' is the definition.
('hag' can be a synonym of 'witch')
'in ancient carthage' is the wordplay.
'in' indicates the answer is hidden within the clue.
'HAG' is hidden within 'ancient carthage'.
(Other definitions for hag that I've seen before include "Witch or ugly old woman" , "Old witch-like woman" , "Crone" .)