If /opt/oss is your target then yes. But I'm assuming it has to be the other way around.
You want to create a link in the directory /opt called oss I imagine and that points to /opt/oss-4.3/oss-ps, right?
So it should be:
ln -s /opt/oss-4.3/oss-ps /opt/oss
That will created a link under /opt named oss and pointing to /opt/oss-4.3/oss-ps. You can check by typing:
If you have color option enabled the link will be in a light blue color. If no enabled it will show like this:
oss -> /opt/oss-4.3/oss-ps