Forbidden urge to which writer's admitted (10)
I believe the answer is:
proscribed
'forbidden urge to which writer's admitted' is the definition.
'proscribed' can be an answer for 'forbidden' (I've seen this before). I'm not sure about the rest of the definition.
'which writer's admitted' is the wordplay.
'which' becomes 'prod' (I can't explain this - if you can you should believe this answer much more).
'writer' becomes 'scribe' (scribe is a kind of writer).
'admitted' means one lot of letters goes inside another (inserted letters are let in or admitted).
'prod' placed around 'scribe' is 'PROSCRIBED'.
Can you help me to learn more?
(Other definitions for proscribed that I've seen before include "on the banned list" , "Forbidden" , "outlawed" .)