"Kaza mkanda wako"

Translation: Tighten your belt

[Renata725212]

Verb - kukaza - I guess that it is causative from kaa. The translation is :
1 fasten, tighten, make tighter, close, compress

2 emphasize, highlight, give emphasis to

3 fix

Passive form from kukaza is kukazwa - be emphasized

[Nsikan9]

If this is the causative form, then what's the verb root?

[AGreatUserName]

My guess is that it's a fairly old causative form of -kaa, meaning "to make stay" and the meaning has changed over time to mean "to fasten", "affix", "make firm".

There is another causative form from -kaa, which is -kalisha, meaning "to settle (someone/something)", "to seat (someone/something)".

[Renata725212]

In my dictionary I don't see the innovative translations of "kukaa" which you wrote :)

[AGreatUserName]

I didn't write any translations of ‑kaa.

The translations I gave were of ‑kaza and ‑kalisha. Read more carefully!