I'd have one to put up with the fool (5)
I believe the answer is:
idiot
'the fool' is the definition.
(thesaurus)
'i'd have one to put up' is the wordplay.
'have' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'put up' says the letters should be written backwards.
'to' written backwards gives 'ot'.
'id'+'i'+'ot'='IDIOT'
'with' acts as a link.
(Other definitions for idiot that I've seen before include "Dunce" , "eg Dostoevski's Myshkin" , "Foolish person" , "The - (Dostoievsky)" , "Sap" .)