Idiot leaves class always pretty bright (6)
I believe the answer is:
clever
'bright' is the definition.
(bright can mean clever or intelligent)
'idiot leaves class always pretty' is the wordplay.
I cannot quite understand how this works, but
'class' could be 'cl' (I've seen this in other clues) and 'cl' is found within the answer.
'always' could be 'ever' (synonyms) and 'ever' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for clever that I've seen before include "expert" , "Quick to learn and understand" , "Smar and canny" , "Adroit, ingenious" , "Smart and ingenious" .)