Staff agreement ignores mass petition (8)
I believe the answer is:
entreaty
'petition' is the definition.
(both can mean a request)
'staff agreement ignores mass' is the wordplay.
I cannot quite see how this works, but
'agreement' could be 'treaty' (treaty is a kind of agreement) and 'treaty' is found in the answer.
The remaining letters 'en' is a valid word 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 entreaty that I've seen before include "Earnest plea" , "Teeny rat (anag.)" , "petition" , "application for assistance" , "Supplication" .)