Re 'Harbour' - I read it as 'To HARBOUR a grudge' is synonymous with 'To NURSE a grudge'.
14d. Blunder by individual turning up hidden bomb, perhaps (5,4) - BOOBY TRAP (hidden bomb)
If 'Blunder' is BOOB or BOOBY, then why is 'Individual PART or PARTY?
19a. Miser, for example returned, after wages, we hear (7) - SCROOGE (Miser)
I can see GE for 'For example returned', but that leaves SCROO for 'Wages we hear' - I assume it's a homophone, but of what? - or am I completely off base?