Worry about Queen getting upset (4)
I believe the answer is:
care
'worry' is the definition.
(I've seen this before)
'about queen getting upset' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'getting upset' shows that the letters should be reversed in order.
'er' written backwards gives 're'.
'ca'+'re'='CARE'
(Other definitions for care that I've seen before include "Worry" , "The provision of what's necessary, for health say" , "Caution, regard for safety" , "See 16" , "Consideration" .)