Burning book in a lounge (6)
I believe the answer is:
ablaze
'burning' is the definition.
(thesaurus)
'book in a lounge' is the wordplay.
'book' becomes 'b'.
'in' is an insertion indicator.
'lounge' becomes 'laze' (I've seen this before).
'a'+'laze'='alaze'
'b' inserted into 'alaze' is 'ABLAZE'.
(Other definitions for ablaze that I've seen before include "On fire - brightly lit" , "Fiercely aflame" , "On fire, burning" , "burnt" , "Fiery" .)