A chap has troublesome issue about new copyist (10)
I believe the answer is:
amanuensis
'copyist' is the definition.
(thesaurus)
'a chap has troublesome issue about new' is the wordplay.
'a chap has' becomes 'aman' (I can't justify this - if you can you should give a lot more credence to this answer).
'troublesome' indicates an anagram.
'about' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'issue' with letters rearranged gives 'uesis'.
'uesis' enclosing 'n' is 'uensis'.
'aman'+'uensis'='AMANUENSIS'
Can you help me to learn more?
(Other definitions for amanuensis that I've seen before include "One assisting writer" , "who may work with dictator?" , "stenographer" , "secretarial post" , "dictator's collaborator, perhaps" .)