Communicate to leave Her Majesty unharmed (6)
I believe the answer is:
intact
'unharmed' is the definition.
(I've seen this before)
'communicate to leave her majesty' is the wordplay.
'communicate' becomes 'interact' (I've seen this in another clue).
'to leave' is a deletion indicator.
'her majesty' becomes 'ER' (Elizabeth Regina).
'interact' with 'er' taken away is 'INTACT'.
(Other definitions for intact that I've seen before include "Not damaged in any way" , "Undamaged, unimpaired" , "Complete - unbroken" , "Unbroken and unimpaired" , "Entire and complete" .)