Volunteers, on an annual occasion, for a sort of show (6)
I believe the answer is:
talent
'sort of show' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe there's a link between them I don't understand?
'volunteers on an annual occasion' is the wordplay.
'volunteers' becomes 'TA' (abbreviation for Territorial Army).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'an annual occasion' becomes 'lent' (I can't explain this - if you can you should believe this answer much more).
'ta'+'lent'='TALENT'
'for a' acts as a link.
Can you help me to learn more?
(Other definitions for talent that I've seen before include "able people" , "Natural ability or flair" , "At Lent (anag.)" , "Clever folk" , "Natural aptitude of an old coin" .)