Bank with international organisation promoted in African region (5)
I believe the answer is:
nubia
'african region' is the definition.
The definition suggests a singular noun which matches the answer.
'bank with international organisation promoted' is the wordplay.
'bank' becomes 'ab' (I can't justify this - if you can you should believe this answer much more).
'with' is an insertion indicator.
'international' becomes 'i' (abbreviation eg in IMF).
'organisation' becomes 'UN' (the United Nations is an organisation).
'promoted' says the letters should be written backwards (going up, in a down clue).
'ab' placed around 'i' is 'aib'.
'aib'+'un'='aibun'
'aibun' backwards is 'NUBIA'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for nubia that I've seen before include "Old African state" , "Upper 16 Across region" , "Ancient African region absorbed into southern Egypt" , "Region of northeast Africa" , "Ancient kingdom" .)