State of mind at the end is fair to middling (9)
I believe the answer is:
temperate
'fair to middling' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I can't see?
'state of mind at the end' is the wordplay.
'state of mind' becomes 'temper' (I've seen this in another clue).
'end' says to take the final letters.
The final letter of 'the' is 'e'.
'temper'+'at'+'e'='TEMPERATE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for temperate that I've seen before include "even" , "Showing moderation" , "Calm" , "pleasant" , "Showing self-restraint" .)