Devil gets involved in pandemonium (5)
I believe the answer is:
'devil' is the definition.
'involved in pandemonium' is the wordplay.
'involved in' indicates a hidden word.
'DEMON' is hidden within 'pandemonium'.
'gets' is the link.
(Other definitions for demon that I've seen before include "Fiend, devil", "Genius", "beast", "ace", "Fallen angel".)