Rabbit-catcher's worry about leading lady (6)
I believe the answer is:
ferret
'rabbit-catcher's' is the definition.
I can't judge whether this definition defines the answer.
'worry about leading lady' is the wordplay.
'worry' becomes 'fret' (to fret about something is to worry).
'about' is an insertion indicator.
'leading lady' becomes 'ER' (Elizabeth Regina).
'fret' placed around 'er' is 'FERRET'.
Can you help me to learn more?
(Other definitions for ferret that I've seen before include "Animal bred for hunting rats and rabbits" , "Rabbit-unearthing animal" , "It drives rabbits from their holes" , "Small member of weasel family, good for catching rabbits" , "Rabbit-hunting polecat" .)