If "beguile" means to charm or enchant:
* Repel
* Repulse
* Alienate
* Disgust
* Offend
* Disenchant
If "beguile" means to deceive or mislead:
* Enlighten
* Inform
* Truthful
* Honest
* Reveal
* Unmask
If "beguile" means to distract or amuse:
* Bore
* Disappoint
* Frustrate
* Depress
The best antonym will depend on the specific situation and the intended meaning of "beguile."