Roman emperor confined in one room (4)
I believe the answer is:
nero
'roman emperor' is the definition.
(Roman emperor, 37-68 AD)
'in one room' is the wordplay.
'in' indicates the answer is hidden within the clue.
'NERO' is hidden in the letters of 'one room'.
'confined' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for nero that I've seen before include "He's reputed to have fiddled while Rome burned" , "Tyrannical Roman emperor" , "Roman Emperor, 54-68 AD" , "Barbarous Roman emperor" , "Emperor who played the fiddle" .)