Gen Y version of a linen mill (10)
I believe the answer is:
millennial
'gen y' is the definition.
Although both the answer and definition are adjectives, I cannot see how one could define the other.
'version of a linen mill' is the wordplay.
'version of' indicates anagramming the letters (another version of the same letters).
'a'+'linen'+'mill'='alinenmill'
'alinenmill' anagrammed gives 'MILLENNIAL'.
Can you help me to learn more?
(Other definitions for millennial that I've seen before include "Relating to a thousand-year period" , "thirtysomething?" .)