Back in Africa is another continent (4)
I believe the answer is:
asia
'continent' is the definition.
(Asia is an example)
'back in africa is another' is the wordplay.
'back' shows that the letters should be reversed in order.
'in' indicates the answer is hidden within the clue.
'aisa' can be found hidden inside 'africa is another'.
'aisa' in reverse letter order is 'ASIA'.
(Other definitions for asia that I've seen before include "Huge landmass" , "A great deal of land" , "Continent of the Hindu Kush" , "Heavily populated area" , "Continent in which India is situated" .)