have an ax to grind
US /hæv ən æks tuː ɡraɪnd/
UK /hæv ən æks tuː ɡraɪnd/

1.
avere un conto in sospeso, avere un secondo fine
to have a private reason for doing or being involved in something, especially a selfish one
:
•
He seems to have an ax to grind with the company, always criticizing their policies.
Sembra avere un conto in sospeso con l'azienda, criticando sempre le loro politiche.
•
I don't have an ax to grind; I'm just stating the facts.
Non ho un secondo fine; sto solo esponendo i fatti.