Disclosed herein is a downhole cleaning apparatus and a method of cleaning a wellbore. The downhole cleaning apparatus has a body and a cleaning element coupled to the body. The cleaning element is selectively moveable in relation to the body from a retracted position to an extended position. When the cleaning element is in the retracted position it is retained by retention formations internal to the tool that are coupled together. The retention formations can be slideably released from one another to enable the cleaning element is able to move to the extended position. The force required to slideable release the retention formations exceeds any forces encountered when the apparatus is run in, preventing premature extension of the cleaning element.