Fool about in small part of desert (5)
I believe the answer is:
dunce
'fool' is the definition.
(both can mean a stupid person)
'about in small part of desert' is the wordplay.
I cannot really see how this works, but
'about' could be 'c' (abbreviation for 'circa') and 'c' is found within the answer.
'part of desert' could be 'dune' (as in a sand dune) and 'dune' is located in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dunce that I've seen before include "Foolish cap wearer" , "Old word for one slow at learning" , "Person slow at learning, bottom of class" , "Boy wearing cap" , "Term of ridicule applied to followers of John Duns Scotus" .)