Well I'm racking my brains for what plant you might mean, because there isn't one called cicyus... can you clarify please, or add a photo? And is this plant in a pot or the ground, and how long have you had it? Do you mean Cistus?

I presume Linda meant Cercis, the Judas Tree, though the flowers come before the leaves on that. Mine has flowered and has now got new green leaves too. Why it would drop leaves I don't know, but there are some scary reasons on the following website.
http://homeguides.sfgate.com/judas-tree-its-diseases-66626.html

I thought cistus as t and y are adjacent on the qwerty key board.
Dryness/wind damage is often a cause but as it tends to keep leaves in mild areas they might just be old last years leaves dropping off.
A photo is needed really.

welcome to GoY too :o)