Factory at first trimmed wages after year in part of Northern England (9)
I believe the answer is:
yorkshire
'year in part of northern england' is the definition.
The definition suggests a singular noun which matches the answer.
'factory at first trimmed wages' is the wordplay.
'factory at' becomes 'york' (I can't justify this - if you can you should believe this answer much more).
'first' becomes 'ist' (ist resembles yst).
'trimmed' means to look at the middle letters (the external letters are trimmed from the word).
'wages' becomes 'hire' (I've seen this in another clue).
The middle of 'ist' is 's'.
'york'+'s'+'hire'='YORKSHIRE'
'after' acts as a link.
Can you help me to learn more?
(Other definitions for yorkshire that I've seen before include "moorland area?" , "English region" , "Cricketing county" , "County (with small terrier?)" , "Largest English county until 1974" .)