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