Looks like it's not getting enough light.
If you live in a frost-free area, that tree could benefit from being outside under the sun. If you live in an area with winter, it could benefit from being in your sunniest (south or west) window--or preferably under a grow light. P. afra likes a lot of light.
Mine always dropped lots of leaves and went into zombie mode when I kept them indoors over winter without supplemental light. This year, I've got them under strong grow lights, and they're keeping nearly as vigorous as they do outside during summer.
I wouldn't do any pruning on yours until it's more vigorous. They're tough trees, and it would probably survive a pruning now, but I actually have managed to kill one by doing heavy work when it was in winter zombie mode. (OK, I did a full trunk chop along with a root prune, but still, the tree would've definitely survived that if I'd done it in summer.)