To find this cache, you'll be walking along Lorong Gaung, which literally translates to "Ravine Lane". As you trek to the cache, you should be able to see why! The path is cut from a steep slope with the valley where the Old Jurong Line used to run on one side, and a slope that leads up to Maju Camp on the other. This road used to be the entrance to Maju Camp, but after Maju Drive was constructed, the road was blocked off and fell into disuse.
The path itself is, fortunately, relatively flat, as long as you stay away from the steep valley on the Jurong Line side. However, like the Jurong Line, after years of neglect, the path has become extremely overgrown, with tree branches and trunks obstructing the way. This jungle-ness is the reason for the terrain rating.
To get ot the cache, all you need to know is that the trailhead is a small path into the undergrowth just after Clementi Neighbourhood Park and before Maju Drive, as you travel northbound along Clementi Road. You'll be able to see the barriers partially hidden in the undergrowth and you'll see a footpath going into the undergrowth. Follow that path to the GZ, and you'll be fine. Someone has placed some markers along the trail, so keep an eye out for them.