On my Spada 3 the Veglia time clock is misted up on the inside of the glass. I would like to get it apart for cleaning but it may be a sealed unit.
The small brass screws in the pics are for the electrical terminals and the larger studs which are used to secure the clock in the main dash panel simply come loose inside the body if the nuts are removed.
I’d remove it to a warm, dry place like an airing cupboard for a while. Seal around the bezel carefully, maybe vaseline or something easily removed if it fails, before reinstatement to see if the problem recurs.
I think you’ll find the lens is plastic and has degraded, it may even be too brittle and crack when you try and remove it.
Its unlikely to clean up.
I found a company that cut custom perspex discs on line and used one of those. Had to drill a hole for the adjuster and bodge a silicon bung to make a seal.
Tbh I can’t remember if it was perspex or acrylic.
Speedy Cables click here will be able to renovate your clock (see here). They are not very speedy though, but in my experience they do a fantastic job. Maybe contact them for a price.
The photo probably doesn’t show it clearly, but I think the problem is inside the plastic, not outside, which is fairly clean. If it will come apart (I haven’t tried yet!!) then it may be possible to clean up or replace the lens. If the front adjuster knob will come off then perhaps the bezel will also. But I may just replace it or send off for refurb, depending on cost.