Stupid piece of abject penitence brought up (5)
I believe the answer is:
inept
'stupid' is the definition.
(thesaurus)
'of abject penitence brought up' is the wordplay.
'of' indicates the answer is hidden within the clue.
'brought up' says the letters should be written backwards (down clues only).
'tpeni' is hidden within 'abject penitence'.
'tpeni' back-to-front is 'INEPT'.
'piece' is the link.
(Other definitions for inept that I've seen before include "Amateurish" , "Incompetent and ineffectual" , "Awkward, showing no skill" , "Absurd or unskilful" , "Unsuitable, clumsy" .)