Glee? It’s unusual for this writer (7)
I believe the answer is:
elegist
'this writer' is the definition.
(elegist is a kind of writer)
'glee? it's unusual' is the wordplay.
'unusual' indicates anagramming the letters.
'glee'+'its'='gleeits'
'gleeits' is an anagram of 'ELEGIST'.
'for' is the link.
(Other definitions for elegist that I've seen before include "bemoaning linesman" , "Kind of writer" , "Gloomy poet" , "Writer of reflective poems" , "Composer of mournful songs" .)