Sinatra is out of stationary - presumably, he'll get it from dancer's boss? (3)
I believe the answer is:
toy
'presumably he'll get it from dancer's boss?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'sinatra is out of stationary' is the wordplay.
'is out of' suggests deleting specific letters.
'stationary' with 'sinatra' removed is 'TOY'.
Can you help me to learn more?
(Other definitions for toy that I've seen before include "Object for a child to play with" , "A child's plaything" , "Doll or teddy, say" , "Trifle with plaything?" , "Trifle or dally with" .)