Attendant drinking a bit of rum, terribly wasted (7)
I believe the answer is:
steward
'attendant' is the definition.
(steward is a kind of attendant)
'drinking a bit of rum terribly wasted' is the wordplay.
'drinking' is an insertion indicator.
'a bit of' indicates taking the first letters.
'terribly' indicates anagramming the letters.
The first letter of 'rum' is 'r'.
'wasted' with letters rearranged gives 'stewad'.
'r' put inside 'stewad' is 'STEWARD'.
(Other definitions for steward that I've seen before include "Crowd-control official" , "College caterer" , "Attendant -- wed star (anag)" , "Airline cabin worker" , "Overseer" .)