One skilled with the needle (10)
I believe the answer is:
inoculator
'one' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for inoculator that I've seen before include "Jabber" , "One who vaccinates" .)