Same nun is a poor secretary (10)
I believe the answer is:
amanuensis
'secretary' is the definition.
(I know that amanuensis is a type of secretary)
'same nun is a poor' is the wordplay.
'poor' is an anagram indicator.
'same'+'nun'+'is'+'a'='samenunisa'
'samenunisa' anagrammed gives 'AMANUENSIS'.
(Other definitions for amanuensis that I've seen before include "stenographer" , "PA" , "secretarial post" , "dictator's collaborator, perhaps" , "Literary assistant - scribe" .)