Clegg has a deteriorating eye condition known as Stargardt's Macular Dystrophy disease giving her only slight peripheral vision in her left eye – she is registered blind. Clegg runs with the aid of guide runner Chris Clarke. She took up athletics aged 9, joining Macclesfield Harriers AC. She originally tried middle distance running and cross country before starting sprinting. In 2006, she competed at the IPC World Championships, winning a silver medal in the T12 200 metres. This was followed by an appearance at the 2008 Summer Olympics, where she won a silver medal in the 100 metres. From 2006 until 2010 her guide runner was Lincoln Asquith. In January 2011, she competed in the IPC World Championships. Whilst there she took a bronze in the 200m. Clegg is a Paralympic silver medallist and current World Champion in the T12 100m and 200m sprints. She was one of the major success stories from the 2011 IPC World Championships in New Zealand and IBSA World Championships in Turkey. In June 2012, Clegg won the 100m and 200m at the IPC Athletics European Championships. Clegg won silver at the London Paralympics on 2 September 2012 in the T12 100m. Clegg and guide Mikail Huggins broke the European record in the final. In October 2012, Clegg won "Para Athlete of the Year" at the Scottish Athletics awards and was presented with her award by fellow GB Paralympian David Weir. She won the award again in October 2013. In 2013, Clegg won double silver at the IPC World Championships in Lyon clocking 12.23 and 25.31 over 100m and 200m respectively. Clegg is sponsored by the property marketing business ESPC where she participated in work experience in 2008 during her time at The Royal Blind School. Her brother, James, also competed in the pool in the S12 category at London 2012. Clegg won the 2014 Commonwealth Games T11/T12 100m with a run of 12.20 seconds, a world-leading time for the year. Due to illness, she was unable to defend her European titles in Swansea shortly after the Commonwealth games. She split with guide runner Mikhail Huggins in 2015. Her new guide runner is Chris Clarke. She was also made to withdraw from the 2015 IPC Athletics World Championships after just one race due to an ankle injury and this also meant that she lost funding from British Athletics. In 2016, she was reclassified as a T11 athlete due to her deteriorating eye condition, requiring her to wear a blindfold while racing. Alongside guide Chris Clarke she won the T11 100m title and 200m title at the 2016 Paralympics.
In October 2018, Clegg announced she was expecting her first child with fiancé Dan Powell in March 2019. They were engaged in October 2017. She has had physical injuries and has been affected by mental health issues. Her guide dog, a black retriever/Labrador cross, is named Hatti. In April 2019 Clegg gave birth to a son, Edward, via emergency C-Section In September 2019 it was announced she would take part in the reality TV series Dancing on Ice.
