Smith gained valuable loan experience at Cambridge United last campaign, helping them to a memorable Conference Play-Off Final 2-1 win against Gateshead at Wembley, and consequently assisting their promotion into League 2.
Smith has been regular starter in Steve Beaglehole’s side this season, most recently pulling off several superb saves in the to West Ham United on Monday at Rush Green.
The shot-stopper will join fellow Under-21s youngster Elder at the Stags and will hope to be involved against second-placed Burton Albion on Saturday, with the possibility of coming up against on-loan City striker Jacob Blyth.