Numb — dead to the world (6)
I believe the answer is:
asleep
I believe this is a double definition.
'numb' is the first definition.
(I've seen this in another clue)
'dead to the world' is the second definition.
(I've seen this in another clue)
(Other definitions for asleep that I've seen before include "Snoozing" , "Inattentive; numbed" , "Dormant, inactive" , "Please be at rest (6)." , "this fast?" .)