A noted new toy, as at Chiswick (4)
I believe the answer is:
eyot
'at chiswick' is the definition.
I can't judge whether this definition defines the answer.
'a noted new toy' is the wordplay.
'a noted' becomes 'e' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'new' indicates an anagram.
'toy' anagrammed gives 'yot'.
'e'+'yot'='EYOT'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for eyot that I've seen before include "Islet found in a river, (especially in England)" , "land in the river" , "Small river island" , "Fawlty Towers waiter" , "Another term for ait" .)