You shot this at 1/60 of a second at F/4.6 with a flash iso 400. (metadata tells all) The issue is depth of field, you need more. If you think of F/number as a fraction it is easier to understand. I'll relate to pie as I male . 1/2 is a very large piece of pie (F/2 is a very large opening) where 1/22 of the pie hardly counts as a piece. (F/22 is a very small opening) have you ever watched some one with poor eye sight look for the glasses by squinting? The small opening creates a sharper picture. If you were glasses you can look though a bit of cardboard and see a sharp picture through it. This is depth of field.

With a flash you should be able to get much more by just controlling the output to a higher amount. If you are using TTL flash (it talks to the camera and you don't need to deal with it much) then you should be able to change the aperture (means hole) to a smaller opening. F/16 perhaps F/22 or greater. The depth of field with out getting needlessly complex is not as much when you are close focused so you need a smaller aperture than you would shooting a landscape.

White balance, your photo is quite blue. I is the background blue white? If so this is bouncing colour onto the snake. If not the balance has shifted raw is slippery when it comes to colour. Every converter shifts a bit and most fail to tag ICC profiles correctly or at all. (adobe!) So editing is done before the computer starts managing colour. depending on the profile you choose to tag the colour can shift dramatically. Monitor colour also plays in too. umm I'll stop here it is a huge discussion insanely complex and technical it is what I spend a ton of time professionally on as I calibrate colour management systems (monitor/ printer and people lol)