Stephen Baxter's men continue to lead the way in the Danske Bank Premier League, after this narrow win at Ferney Park.
The Mallards had their chances and should have been 2 ahead within the opening 15 minutes only for some heroic defending.
Johnny Lafferty appeared to be through on goal but took an extra touch which allowed Howard Beverland enough time to make a block, but in his second chance, Lafferty hit the ball early and it rebounded off the crossbar, with Gault blocking Shane McGinty's follow up.
Crusaders got the only goal of the game on 27 minutes when Jordan Forsythe ran unchallenged through the midfield, and struck low into the bottom left corner of the net.
There wasn't much between the sides in the second half with Cushley striking the bar and despite pushing for a late equaliser, the home side couldn't find the goal that they would have deserved.
The U20s also tasted defeat, going down 6-2 to Crusaders Reserves with Quinn and Coalter the scorers.