1. To explain or make something clear in an honest and genuine manner, without deception or hidden motives
I want to clarify sincerely that I had no intention to offend you.
Quero esclarecer sinceramente que não tinha intenção de ofendê-lo.
2. To provide transparent and truthful explanation about a confusing matter
The CEO decided to clarify sincerely the reasons behind the company's decision.
O CEO decidiu esclarecer sinceramente os motivos por trás da decisão da empresa.