Watch Kelvin, stuck in toilet, unconscious (7)
I believe the answer is:
lookout
'watch' is the definition.
('lookout' can be a synonym of 'watch')
'kelvin stuck in toilet unconscious' is the wordplay.
'kelvin' becomes 'k' ('K' can be a synonym of 'kelvin').
'stuck in' means one lot of letters goes inside another.
'toilet' becomes 'loo' (loo is a kind of toilet).
'unconscious' becomes 'out' ('out' can be similar in meaning to 'unconscious').
'loo'+'out'='looout'
'k' put into 'looout' is 'LOOKOUT'.
(Other definitions for lookout that I've seen before include "Guard on duty" , "One who keeps watch, a sentry" , "A sentry or guard, must be watchful" , "Vantage point" , "View" .)