Overtures of moggy's emission of wailing call (4)
I believe the answer is:
meow
'call' is the definition.
(thesaurus)
'overtures of moggy's emission of wailing' is the wordplay.
'overtures of' suggests taking the first letters (I've seen 'overtures' mean this).
The first letters of 'moggy emission of wailing' is 'MEOW'.
(Other definitions for meow that I've seen before include "Cat's cry" , "Crying sound of an animal" , "Catty remark" , "Beastly noise" , "reply to spiteful dig" .)