They avail themselves of escorts when hotel's deserted (5)
I believe the answer is:
users
'they avail themselves' is the definition.
The definition suggests an adverb but the answer is not.
'of escorts when hotel's deserted' is the wordplay.
'of escorts' becomes 'us' (I am not sure about this - if you are sure you should believe this answer much more).
'when' becomes 'e' (I've seen this in other clues).
'hotel's' becomes 'ritzs'.
'deserted' suggests removing the centre.
'ritzs' with its centre removed is 'rs'.
'us'+'e'+'rs'='USERS'
Can you help me to learn more?
(Other definitions for users that I've seen before include "Operators" , "Customers" , "Drug addicts" , "subscribers" , "Ruses for employers" .)