Pandemonium as Charles embraces Oscar (5)
I believe the answer is:
chaos
'pandemonium' is the definition.
(synonyms)
'charles embraces oscar' is the wordplay.
'charles' becomes 'Chas' (shortened form).
'embraces' indicates putting letters inside.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'chas' enclosing 'o' is 'CHAOS'.
'as' acts as a link.
(Other definitions for chaos that I've seen before include "disarray" , "State of extreme confusion and disorder" , "Totally disordered state" , "A total shambles" , "Absence of order" .)