Rain ensues when Her Majesty attends event (6)
I believe the answer is:
shower
'rain' is the definition.
(I know that shower is a more specific form of the action rain)
'ensues when her majesty attends event' is the wordplay.
I cannot quite see how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'event' could be 'show' (show is a kind of event) and 'show' is found within the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for shower that I've seen before include "Rabble - downfall" , "Fall of rain; slack people (slang)" , "awful group of people" , "One who indicates way" , "One displaying - short spell of rain" .)