Old rendition of most awful passage by Spooner (9)
I believe the answer is:
erstwhile
'old' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for erstwhile that I've seen before include "Quondam" , "Formerly" , "Former, previous" , "Former - list where (anag)" , "In the past" .)