Example of prime-time entertainment: these characters are densest (10)
I believe the answer is:
eastenders
'example of prime-time entertainment these' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'characters are densest' is the wordplay.
'characters' indicates an anagram.
'are'+'densest'='aredensest'
'aredensest' with letters rearranged gives 'EASTENDERS'.
(Other definitions for eastenders that I've seen before include "TV programme" , "Cockneys" , "Soap, for example" , "BBC TV series" , "TV soap" .)