Singer of extra special tone? (4)
I believe the answer is:
alto
'singer' is the definition.
(alto is a kind of singer)
'of extra special tone?' is the wordplay.
'of' indicates the answer is hidden within the clue.
'ALTO' can be found hidden inside 'extra special tone'.
(Other definitions for alto that I've seen before include "Male singer" , "Low female singing voice" , "Member of choir" , "Singer's hidden inside chemical toilet" , "High male singing voice" .)