I found a better paying job. I tendered my resignation. Employer said no due to a 1 year contract. Is that enforceable?

Yes, but how likely is it the employer will sue you?  Probably not, and you have defenses you could raise.

An employer cannot force you to work for it.  However, in some circumstances usually involving employees with specialized skills, the employer may be able to force you not to work for anyone else for the length of your employment contract.  For example, it is unlikely that McDonalds could force a counter clerk to either work for it or refrain from working, even if the clerk had signed an employment agreement.  On the other hand, the Knicks absolutely could force Phil Jackson to either work for them or not work at all during the length of his employment agreement with them.