Register a tendency to sneer at the audience (9)
I believe the answer is:
listeners
'the audience' is the definition.
(people listening to something)
'register a tendency to sneer' is the wordplay.
I cannot really see how this works, but
'register' could be 'list' (listing is a kind of registering) and 'list' is located in the answer.
an anagram of 'sneer' is 'eners' which is within the answer.
No letters remain.
This explanation may well be incorrect...
'at' is the link.
Can you help me to learn more?
(Other definitions for listeners that I've seen before include "Hearers" , "Radio fans" , "Performers of tap" , "Those who pay attention" , "The audience" .)