Holy woman, a Bishop Elizabeth (6)
I believe the answer is:
abbess
'holy woman' is the definition.
'a bishop elizabeth' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'elizabeth' becomes 'bess'.
'a'+'b'+'bess'='ABBESS'
(Other definitions for abbess that I've seen before include "Religious leader" , "Head of convent" , "Head nun" , "Person in charge of convent" , "superior to her sisters!" .)