Worry about Queen being upset (4)
I believe the answer is:
care
'worry' is the definition.
(eg without a care means without a worry)
'about queen being upset' is the wordplay.
'about' becomes 'ca' (circa).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'being upset' is a reversal indicator.
'er' back-to-front is 're'.
'ca'+'re'='CARE'
(Other definitions for care that I've seen before include "Have affection (for)" , "See 16" , "Feel concern or interest" , "Mind" , "Caution, regard for safety" .)