Sutra:
149. "saraNam" - ishta prApthikkum anishta nivAraNaththukkum thappAdha upAyamAga.

Meaning:
The meaning of the word "sharaNam" is now explained. Its meaning is that it is the guaranteed means for gaining that which is seeked and avoiding that which is not wanted.

Sri PBA Swami's Sarartha Deepikai:
The second part of the dvaya mantra is "sharaNam". Its meaning is that it is the guaranteed way of gaining that which is desired and leaving out that which is not wanted.

Ignorance, the likes and dislikes that come out of it and the good and bad actions (karmas) are that which are not wanted. Going in the path of archirAdhi, seeking His divine abode, seeing His divine form and being in His service are that which are seeked. And this term is the for-sure means to gain those things which are desired and avoiding those things that are undesired.