What happens to clearance?

So I currently have a Secret clearance with DoD (tier 3 investigation). About a year ago I was offered a job with a DoD contractor that I never took. Fast forward today, I was offered a position through a contractor for CBP; it is a public trust hight risk because I’ll be armed. Question is, what happens to my clearance, and is this public trust a tier 5 investigation, what is the difference?

Tier 5 = TS

Secret is still active for ten years. Once you have the TS, Secret is inconsequential.

10 years. Even if I don’t use it?

I should have said current. It is still current. Periodic reinvestigatiins can be triggered at any time

So my secret will be current for 10 years even though I don’t use it and will be employed under public trust high risk?