Ambassador occupying middle of area is former Asian president (4)

'former asian president' is the definition.
(Syngman Rhee, former president of South Korea)

'ambassador occupying middle of area' is the wordplay.
I cannot quite see how this works, but
'ambassador' could be 'he' (His or Her Excellency) and 'he' is found within the answer.
The remaining letters 're' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).

'is' acts as a link.