I cheat terribly, last character in school to be moral (7)
I believe the answer is:
ethical
'moral' is the definition.
(synonyms)
'i cheat terribly last character in school' is the wordplay.
'terribly' indicates an anagram.
'last character in' indicates one should take the final letters.
The last letter of 'school' is 'l'.
'i'+'cheat'='icheat'
'icheat' with letters rearranged gives 'ethica'.
'ethica'+'l'='ETHICAL'
'to be' is the link.
(Other definitions for ethical that I've seen before include "Conforming to accepted standards of behaviour" , "At Chile (anag.)" , "Morally correct, in accordance with principles" , "lt's available on prescription only" , "Abiding by moral principles" .)