Assembling penal judges (5)
I believe the answer is:
panel
'judges' is the definition.
'assembling penal' is the wordplay.
'assembling' indicates anagramming the letters.
'penal' is an anagram of 'PANEL'.
(Other definitions for panel that I've seen before include "Team selected, to judge a competition perhaps" , "regularly beaten by bodywork experts?" , "Wall mounting" , "Group judging a contest" , "Team of judges" .)