Mitch Marsh's guts upset by end of Ashes feast (9)
I believe the answer is:
christmas
'feast' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'mitch marsh's guts upset by end of ashes' is the wordplay.
'guts' indicates the central letters (the insides of the word).
'upset by' indicates anagramming the letters.
'end of' says to take the final letters.
The middle of 'marsh' is 'ars'.
The final letter of 'ashes' is 's'.
'mitch'+'ars'='mitchars'
'mitchars' anagrammed gives 'christma'.
'christma'+'s'='CHRISTMAS'
Can you help me to learn more?
(Other definitions for christmas that I've seen before include "Not in general use" , "The festive season harms tics, oddly" , "SECOND PART OF 1 ACROSS" , "Winter feast" , "Religious festival" .)