The incident happened between 15:46pm and 16:07pm behind the Loco Shop on the corner of Convent Road and Feltham Hill Road.
The victim was struck on the forehead resulting in cuts, and had a sum of money stolen from their wallet.
The suspect is described as a White man, 5”9, well-built with ear length brown hair and a long beard, wearing trainers with white soles.
Anyone with information is urged to contact police on 101.
