Bishop enters a lounge that's brightly lit (6)
I believe the answer is:
ablaze
'brightly lit' is the definition.
(I've seen this in another clue)
'bishop enters a lounge' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'enters' is an insertion indicator.
'lounge' becomes 'laze' (as in to lounge or lie around).
'a'+'laze'='alaze'
'b' going within 'alaze' is 'ABLAZE'.
'that's' is the link.
(Other definitions for ablaze that I've seen before include "Fiercely aflame" , "On fire, burning" , "burnt" , "Flaming; on fire" , "Well-lit" .)