What queen might do — panic! (4,7)
I believe the answer is:
have kittens
I believe this is a double definition.
'what queen might do' is the first definition.
(a female cat is a queen)
'panic' is the second definition.
(to have kittens is to panic)
(Other definitions for have kittens that I've seen before include "Blow up" , "produce cute delivery" , "Be extremely nervous (as a queen might)" , "Shake with nerves" .)