The haze is most likely on the surface behind the aperture.
Get a lens spanner (US 20-30 or so on ebay). Take off the brass ring that you see from behind, next to the RF cam. Than you can take the lens barrel out of the helix.
Then, using a cleaning cloth and some force you can take off the rear element group for cleaning. Before you unscrew it, mark it so when you reassemble you know how tight to go.
The above works for both, chrome and black/chrome versions of this lens.
If it is the black/chrome version, you will find a tiny screw in front of the aperture ring. If you take this out you can remove the front group of the lens without spanner, and get access to surfaces behind and in front of aperture for cleaning.
Best,
Roland.