A bishop with extraordinary zeal, on fire (6)
I believe the answer is:
ablaze
'on fire' is the definition.
(synonyms)
'a bishop with extraordinary zeal' is the wordplay.
'bishop' becomes 'B' (abbreviation for bishop in chess).
'with' means one lot of letters go next to another.
'extraordinary' indicates anagramming the letters.
'zeal' is an anagram of 'laze'.
'a'+'b'+'laze'='ABLAZE'
(Other definitions for ablaze that I've seen before include "being toasted?" , "Fiercely aflame" , "filled with anger" , "Bright" , "On fire - brightly lit" .)