Messages ending bygone custom via papyri: small progress? (6)
I believe the answer is:
emails
'messages' is the definition.
(emails are electronic messages)
'ending bygone custom via papyri small progress?' is the wordplay.
'ending' says to take the final letters.
The final letters of 'bygone custom via papyri small progress' are 'EMAILS'.
(Other definitions for emails that I've seen before include "Electronic messages" , "Computer communications" , "Electronic communications" .)