Worry about the queen’s hunt (6)
I believe the answer is:
ferret
'hunt' is the definition.
(I've seen this before)
'worry about the queen's' is the wordplay.
'worry' becomes 'fret' (fretting is a kind of worrying).
'about' means one lot of letters goes inside another.
'the queen' becomes 'er' (Elizabeth Regina).
'fret' placed around 'er' is 'FERRET'.
(Other definitions for ferret that I've seen before include "Small fierce animal, rabit hunter" , "Small animal used to drive rabbits from burrows" , "Search; type of polecat" , "Tame polecat" , "It digs out rabbits" .)