In a hotel, enthralled by scholarly book (2,4)
I believe the answer is:
at home
'in' is the definition.
(someone at home is 'in')
'a hotel enthralled by scholarly book' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'enthralled by' means one lot of letters goes inside another ('enthral' can mean 'capture').
'scholarly book' becomes 'tome' (I've seen this before).
'h' put within 'tome' is 'thome'.
'a'+'thome'='AT-HOME'
(Other definitions for at home that I've seen before include "Familiar with" , "In one's own house" , "celebration" , "Reception in one's own abode" , "In (for a party?)" .)