An irritated doyen describing his state of mind (7)
I believe the answer is:
annoyed
'his state of mind' is the definition.
The definition suggests a singular noun but the answer is not.
'an irritated doyen' is the wordplay.
'irritated' is an anagram indicator (I've seen this in other clues).
'doyen' is an anagram of 'noyed'.
'an'+'noyed'='ANNOYED'
'describing' is the link.
Can you help me to learn more?
(Other definitions for annoyed that I've seen before include "Irritated, peeved" , "'Harassed, pestered (7)'" , "Upset" , "Anodyne (anag.)" , "put out" .)