More natural options:
* Please contact me if you have any questions.
* If you need any clarification, please don't hesitate to contact me.
* Feel free to contact me if you require further explanation.
Why the original is awkward:
* "Kindly" sounds a bit formal and old-fashioned.
* "Need any clarification" is a bit clunky. It's better to use "have any questions" or "require further explanation" for smoother flow.
Choose the option that best fits the tone and context of your message.