Originally an actor, Clegg moved on to write for radio. She wrote an adaptation of The Chrysalids. She went on to write for television, including a number of scripts for shows such as Coronation Street and Crossroads. Eventually, she came to write for Doctor Who, largely because her children were fans.
The 2|entertain documentary Single Write Female explored Clegg's career as an actor and a writer. It was titled so as she was the first female writer on the show.