citrus family is mostly safe.
as far as whether it will thrive inside a chameleon enclosure, that's a whole different game.
Idk much about it since i am more of "using the chameleon keeper traditional plants type" kinda guy.
I don't think there is enough light indoors to produce fruit on trees unless you have some sort of high intensity discharge light above your cham cage. 4 or so linear fluorescent plant lights might do the trick, but I don't know how the chameleon would feel about that. I have often thought of buying a few lemon and lime trees for my chameleon to put outside, though.