hard to tell at this stage
but it looks a lot like a leaf bud ....
sometimes, but not always ... adeniums in a semi-dormant state (or phase) will develop leaf buds that are "curled" - and that's what I think we see here
once emerged, the leaf margins will be "wavy" and distorted ....later, these wavy shaped leaves will fall off
in the case with adeniums....the cause is from not watering - or too little water - but that is actually good - and signifies the plant is in a drought or dry period -
just what we want during the winter months ...nice and dry
despite what the plant is saying......I would not water ....