Don't insist on greeting being heard (5)
I believe the answer is:
'don't insist on' is the definition.
(I've seen this before)
'greeting being heard' is the wordplay.
'greeting' becomes 'wave' (I've seen this before).
'being heard' indicates a 'sounds like' (homophone) clue.
'wave' is a homophone of 'WAIVE'.
(Other definitions for waive that I've seen before include "Forgo right or claim", "Refrain from insisting on right or privilege", "Refrain from insisting on right or claim", "Dispense with, forgo", "pass up".)