President upset writer touring Delaware … (5)

I believe the answer is:

biden

'president' is the definition.
(Joe Biden)

'upset writer touring delaware' is the wordplay.
'upset' says the letters should be written backwards.
'writer' becomes 'nib' (something which writes).
'touring' means one lot of letters goes inside another (touring can mean going round).
'delaware' becomes 'DE' (standard two letter abbrev).
'nib' backwards is 'bin'.
'bin' enclosing 'de' is 'BIDEN'.

I've seen this clue in The Guardian.

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