Article about one old African leader providing health supplement (8)
I believe the answer is:
thiamine
'health supplement' is the definition.
The definition suggests a singular noun which matches the answer.
'article about one old african leader' is the wordplay.
'article' becomes 'the' (the definite article in English).
'about' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'old african leader' becomes 'amin' (I can't explain this - if you can you should give a lot more credence to this answer).
'i'+'amin'='iamin'
'the' placed around 'iamin' is 'THIAMINE'.
'providing' acts as a link.
Can you help me to learn more?
(Another definition for thiamine that I've seen is " Aneurin".)