Animals the queen worries about (7)
I believe the answer is:
ferrets
'animals' is the definition.
The answer is an example.
'queen worries about' is the wordplay.
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'worries' becomes 'frets' (fretting is a kind of worrying).
'about' means one lot of letters goes inside another.
'er' going within 'frets' is 'FERRETS'.
'the' is the link.
(Other definitions for ferrets that I've seen before include "Albino polecats" , "Polecats for catching rabbits" .)