Instruct how to cheat (5)
I believe the answer is:
teach
'instruct' is the definition.
(I know that instruct can be written as teach)
'how to cheat' is the wordplay.
'how' indicates an anagram (I've seen this in other clues).
'cheat' with letters rearranged gives 'TEACH'.
(Other definitions for teach that I've seen before include "Give instruction to" , "Blackbeard" , "Impart knowledge" , "show" , "Work in school" .)