It's less risky for tops to bareback than for bottoms, but that doesn't mean there's no risk. The fact that someone says he's HIV- means nothing: he may by positive and not know it, or he may be lying. The risk to you is much, much higher if your partner has recently become HIV+ and isn't on treatment.

Yes, you should be tested. Contact your local sexual health clinic to find out what kinds of HIV tests they offer and on what schedule you should be getting tested. If you're sexually active, especially with multiple partners and/or strangers, you should be tested regularly anyway.

Two other things: people who are HIV+ and are on treatment and are undetectable cannot transmit HIV. And don't call it "clean." Having HIV doesn't make you dirty.