Clarke, 27, joins the Reds from Notts County Ladies to bolster the team’s attacking options ahead of the upcoming FA Women’s Spring Series.
Midfielder Coombs spent the 2016 season on a year’s loan with Scott Rogers’ side and has now returned to the club in a permanent move.
Clarke is a clinical striker who came through the youth setup at Leeds Carnegie Ladies before joining Notts County Ladies in 2010, spending the last six seasons with the Lady Magpies.
She said: “I am delighted to join Liverpool Ladies and I’m really looking forward to working alongside the players and Scott.