How was it lent to the business? Was it direct, or was it to the director and the director put it in?
If it was directly lent to the business, then you would normally set up a loan account. These posts explain it in some more detail:
http://community.quickfile.co.uk/t/accounting-for-loans/1375/2?u=qfsupport
If it was lent to the director as a “personal loan”, and then the director put it into the business, it would be treated as a transfer from the Director’s loan account. You would simply tag the repayments as a transfer back to that bank account to show it as repaid.