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' indicates putting letters inside.
'er' put into 'frets' is 'FERRETS'.
'the' is the link.
(Other definitions for ferrets that I've seen before include "Albino polecats" , "Polecats for catching rabbits" .)