Explode, as fool stands on foot (2,3)
I believe the answer is:
'explode' is the definition.
(going off is a kind of exploding)
'fool stands on foot' is the wordplay.
I cannot quite understand how this works, but
'fool' could be 'goof' (goof is a kind of fool) and 'goof' is found within the answer.
'foot' could be 'f' (abbreviation) and 'f' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'as' is the link.
Can you help me to learn more?
(Other definitions for go off that I've seen before include "Fire" , "Explode" , "discharged" , "Rot; leave" , "Decay - become disenchanted with" .)