Talk to Irnskar about Octieve

Walkthrough
If the Dragonborn speaks with Octieve San at The Winking Skeever, he will tell of his debt to Irnskar Ironhand. The Dragonborn can then offer to speak with Irnskar about the debt.

Talk to Irnskar about Octieve
Irnskar will either be at home at Thane Bryling's house or walking around Solitude. If the Dragonborn's speech skill is sufficiently high, a simple talking-to (a persuade) will suffice. Otherwise, intimidation might be necessary. Or, heaven forbid, the Dragonborn could pay off the debt, 538 (L53).

Tell Octieve that Irnskar is taken care of
Return to Octieve to receive the reward. Sprich mit Irnskar über Octieve