Disciplinary panel assembled (5)

I believe the answer is:

penal

'disciplinary' is the definition.
(thesaurus)

'panel assembled' is the wordplay.
'assembled' indicates an anagram.
'panel' with letters rearranged gives 'PENAL'.

(Other definitions for penal that I've seen before include "Involving punishment as by the law" , "Punishable by law" , "Deliberately unpleasant" , "Punishing" , "Corrective" .)

I've seen this clue in The Telegraph.

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