Can i use half a packet of brewers yeast and store the rest?

EC-118 yeast. I am thinking about oxidization of the stored half, thought i could wrap it in clingfilm and put it in the fridge, will this preserve it?
You could but it would be better to use the whole packet, even if if is more than what is called for with your batch size. The extra will get you started faster and help insure that wild yeasts and bacteria do not start breeding in your wine.
Yeast is cheap, cheap, cheap. Just dump the unused and buy new next time.