Nothing featured in new online talks is well-known (5)
I believe the answer is:
noted
'well-known' is the definition.
(I've seen this before)
'nothing featured in new online talks' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'featured in' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'online talks' becomes 'ted' (TED Talks).
'n'+'ted'='nted'
'o' put within 'nted' is 'NOTED'.
'is' acts as a link.
(Other definitions for noted that I've seen before include "Illustrious" , "Observed - famous" , "Well known; registered" , "Remarkable" , "Significant" .)