Thus denied start, stopped by this writer's boss (8)
I believe the answer is:
eminence
'boss' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'thus denied start stopped by this writer's' is the wordplay.
'thus' becomes 'hence' (synonyms).
'denied start' means to remove the first letter.
'stopped by' indicates putting letters inside (I've seen this in other clues).
'this writer's' becomes 'mine' (belonging to the crossword setter).
'hence' with its first letter taken away is 'ence'.
'ence' placed around 'mine' is 'EMINENCE'.
Can you help me to learn more?
(Other definitions for eminence that I've seen before include "Position of higher distinction" , "State of distinction, like cardinal" , "Acknowledged superiority; piece of rising ground" , "High status importance" , "cardinal's address" .)