If I were you, I wouldn't have bought the share when I know it was speculated, but since you have bought it, you could either hold on to it and see if TNB is going to get another tariff hike next year, or sell now to cut loss.
Remember, TENAGA surged RM2 in 2 trading days, all based on speculation.
Imagine if PNB and Khazanah sell more of their stake in TENAGA in the open market, how low would the price go?
It could be back to around RM7 or RM7.50, where it is more sustainable, until further developments.

This is just my point of view. You should do your due diligence when deciding.