Post-match expense? Some will involve flash car (7)
I believe the answer is:
alimony
'post-match expense?' is the definition.
I can't judge whether this defines the answer.
'will involve flash car' is the wordplay.
'will' becomes 'any' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'involve' indicates putting letters inside.
'flash car' becomes 'limo' (limousine, a fancy car).
'any' enclosing 'limo' is 'ALIMONY'.
'some' is the link.
Can you help me to learn more?
(Other definitions for alimony that I've seen before include "financial support separately provided" , "Money paid under court order to divorced wife" , "Payment ordered by court to divorced woman" , "Support paid by one spouse to another" , "Allowance due to be paid after separation" .)