You can not sent money to a guest who never had a confirmed reservation with you.
Cleaning fees are anyway related to a confirmed reservation, so charging them without is not normal Airbnb procedure. As an alternative you could add them to a reservation in future for the same guest or sent the guest a special offer for 1 night stay for(about) price of the fee (i noticed your normal cleaning fee is Euro 49,-, but be aware of service costs for both of you). By maybe take your loss and be prepared not having same "circumstances" in future ?