A delivery system having a steerable delivery device and an elastic clip for treating an internal tissue defect, such as septal defects and the like, is provided. The clip can be deformable between a relaxed state and a stressed state and biased towards the relaxed state. The delivery device can include a flexible tubular needle with a lumen for housing the clip while in the stressed state. When used to treat a septal defect, the needle is advancable through overlapping tissue flaps and a pusher member is advancable within the needle lumen to push the clip distally such that one end of the clip is deployed and engages a tissue flap. The needle can then be retracted allowing the clip to deploy over both flaps of tissue, where the biasing force returns the clip to the relaxed state drawing the tissue flaps together and closing the septal defect.