Checked mass reaches five hundred (8)
I believe the answer is:
serviced
'checked' is the definition.
('service' can be a synonym of 'check')
'mass reaches five hundred' is the wordplay.
I cannot really see how this works, but
'mass' could be 'service' (Mass is a type of church service) and 'service' is found within the answer.
'five hundred' could be 'd' (Roman numeral for 500) and 'd' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for serviced that I've seen is " Reconditioned".)