"Communication is the art of being understood." Peter Ustinov
"I've clarified this already" is a statement that many of us are prone to use when we find ourselves for the umpteenth time repeating ourself. When we believe we have said everything we meant to say, and especially when we have said it more than once, we tend to believe that we have adequately communicated.
This commonly held point-of-view (guilty here too!) assumes that the recipient of the message is the one accountable for understanding us. We become frustrated that they "don't get it" or have to be told multiple times in multiple ways. And of course we forget that the responsibility for effective communication is mutual. As the sender of the message we may be even more responsible than the receiver.
As the originator of a message, a leader has to (a) acknowledge his or her responsibility in the process,
(b) be sensitive to the signals received as feedback and (c) have a willingness to change the communication process if it isn't working. The pride of being right about who is having the problem can easily get in the way of addressing a crucial communication issue. Start first with you.
Of course as recipients we also need to learn to listen and take charge of getting the information we need to understand the message. But ultimately, if you are going to be an effective leader, you must also take a leadership role in communication. If you are not being understood, the place to start in finding the problem is likely to be in the mirror.