Condemn poor scholar holding one up (8)
I believe the answer is:
denounce
'condemn' is the definition.
(I know that condemn is a more specific form of denounce)
'poor scholar holding one up' is the wordplay.
'poor scholar' becomes 'dunce' (I've seen this before).
'holding' is an insertion indicator.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'one' back-to-front is 'eno'.
'dunce' placed around 'eno' is 'DENOUNCE'.
(Other definitions for denounce that I've seen before include "attack" , "Speak publicly against, expose" , "Publicly declare to be wrong" , "Revile" , "Speak publicly against, censure" .)