Forbid misuse of bread (5)
I believe the answer is:
debar
'forbid' is the definition.
(debarring is a kind of forbiding)
'misuse of bread' is the wordplay.
'misuse of' is an anagram indicator (I've seen this in other clues).
'bread' with letters rearranged gives 'DEBAR'.
(Other definitions for debar that I've seen before include "Blackball" , "Ban" , "Black" , "Keep out" , "Shut out, preclude" .)