He's entertained in vague style (5)
I believe the answer is:
guest
'he's entertained' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'in vague style' is the wordplay.
'in' indicates a hidden word.
'GUEST' is hidden within 'vague style'.
Can you help me to learn more?
(Other definitions for guest that I've seen before include "Person receiving another's hospitality" , "Visitant" , "Hotel resident" , "Conjectured audibly" , "Invitee" .)