In the state of NC can wages be withheld in the event a sign-on bonus was offered for employment?

My contract states the following: 1. Amount of Sign-On Bonus. Upon commencing employment with xxxxxx (defined as arriving for your first day of work), you will be entitled to a Sign- on Bonus, subject to applicable tax withholdings, in the amount of 8k which will be payable as follows: a. 8k to be paid as soon as administratively feasible after your date of hire 2. No Contract of Employment. This sign-on bonus should not be construed as modifying your “at-will” employment status nor creating a guaranteed right of future employment. You remain free to end your employment with xxxxxxx at any time, with or without notice, and xxxxxx retains the corresponding right. 3. Repayment for Voluntary Termination or Termination for Cause. If you voluntarily terminate employment with xxxxxx or are terminated for “cause” within twenty-four (24) months of your start date, you will be obligated and agree to repay xxxxxx any portion of the sign-on bonus that you have received as of the date of your separation of employment with xxxxxx.