A man entered a shop in Kirklington Road with a knife at around 10.40am on October 19.
He threatened the shop assistant and got away with cash.
The man in the photo is described as white, 5ft 7in tall and in his early 20s.
He was wearing dark trousers, a black hooded jacket with a black t-shirt underneath which had a white design on it and a black balaclava.
He spoke with a local accent.
A Nottinghamshire Police spokesman said: "It's believed he came from the direction of Kirklington Road and left turning right on to Top Street heading towards the field which leads to the bypass.
"If you saw this man or have any information that can help, please contact us on 101, quoting incident 227 of October 19.
"You can also contact Crimestoppers anonymously on 0800 555 111."