Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means blink and the verb vocab version is to blink.

This word is generally used in the phrase 瞬く間に (in the blink of an eye).

Mah ta-ta (またた) is showing, causing you to blink. I don't know what a "ta-ta" is, but I bet you could come up with something that's blink-worthy.