Foolish person unaltered? I will go (3)
I believe the answer is:
ass
'foolish person' is the definition.
(ass can mean a foolish person)
'unaltered? i will go' is the wordplay.
'unaltered?' becomes 'as is' (ie something left 'as is').
'will go' suggests deleting specific letters.
'asis' with 'i' taken away is 'ASS'.
(Other definitions for ass that I've seen before include "Long-eared animal" , "Moke" , "Silly fool or beast of burden" , "Donkey or foolish person" , "Jennet" .)