Benefactors having no right to infiltrate parties (6)
I believe the answer is:
donors
'benefactors' is the definition.
(I know this)
'no right to infiltrate parties' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to infiltrate' indicates putting letters inside.
'parties' becomes 'dos' (do is a kind of party).
'no'+'r'='nor'
'nor' put within 'dos' is 'DONORS'.
'having' is the link.
(Other definitions for donors that I've seen before include "They give things including blood" , "They give, blood say" , "Givers as of blood" , "They give, money or blood" , "They give to others, maybe blood" .)