Anything is fixable just depends on how much you are prepared to spend. The photo isn’t really that good as to show what and where it is. So post a couple more photos to give us a better idea of what is broken
Would've thought it was pretty obvious to you guys what it was. It's the right-hand mirror stem snapped off the base.
Plastic to plastic can be eaisily glued and would be just as strong, with the right glue. Might look a little bodged so it depends on how much you want it to look "right".
Agree with the above a good epoxy resin glue and tape it for 24 hrs best removed from bike to get a good repair.
PU adhesive used with activator would be my choice. If it can hold a car windscreen it'll work for that. Flexible bond will resist vibration. https://www.christinedemerchant.com/adhesive-glue-polyurethane.html
@Flashp Well said on the PU! I swear by it as I use it on everyday repairs. Didn’t know it could be activated though?
In the past I've seen an activator available, it gets painted on one half and adhesive goes on the other. Thin clear liquid as I recall. It still works well without though.
Many years ago when the second series Vauxhall’s cavalier came out we were always fixing rust on the rear tailgates and the then ‘new idea’ bonded screen always had to come out. At the time we did always black etch prime the frame first.