Hullaballoo in opium den, man recollected (11)
I believe the answer is:
pandemonium
'hullaballoo' is the definition.
(both can mean a chaotic situation)
'opium den man recollected' is the wordplay.
'recollected' indicates an anagram.
'opium'+'den'+'man'='opiumdenman'
'opiumdenman' anagrammed gives 'PANDEMONIUM'.
'in' acts as a link.
(Other definitions for pandemonium that I've seen before include "State of chaos" , "Bedlam" , "Chaos and confusion" , "mayhem" , "havoc" .)