Where's the sound coming from? Cat getting round a queen (6)
I believe the answer is:
larynx
'where's the sound coming from?' is the definition.
(medical term for the voice box)
'cat getting round a queen' is the wordplay.
'cat' becomes 'lynx' (lynx is a kind of cat).
'getting round' is an insertion indicator.
'queen' becomes 'r' (r is abbreviation regina. e.g. in ER ).
'a'+'r'='ar'
'lynx' going around 'ar' is 'LARYNX'.
(Other definitions for larynx that I've seen before include "The formal voice box" , "Where growls come from" , "box of cords?" , "Site of the vocal cords" , "part of pipe" .)