PRWeek revealed MacLaverty left Hotwire in February to pursue a new challenge.
Clarity said her appointment follows "a period of rapid expansion and significant investments", including the acquisition of San Francisco-based firm DRSmedia and the recruitment of UK MD Rachel Gilley from Bite and Alexander Fink to lead the agency’s efforts in the UK, Germany, Austria and Switzerland.
"We’re in the process of transitioning from a small entrepreneurial agency into a more mature, mid-size firm," Clarity PR founder and CEO Sami McCabe said.
"For some time we’ve felt that having a seasoned agency leader on the global leadership team would be enormously helpful as we navigate this process and execute against our growth strategy.
"Following an extensive search, we identified Alex as the perfect person for the role: her first-hand experience of playing a pivotal role in the growth of an agency we’ve long-admired will doubtless prove invaluable in the coming months and years."
MacLaverty said Clarity is the ideal agency for her next challenge, with "big ambitions, an exceptionally talented team, and an amazing energy and drive that comes from a truly entrepreneurial mindset".
She added: "I love that it is doing things differently - investing in technology, working with genuine disruptors, taking risks - and I am really excited to be part of the next stage of its growth."