you can mask it out with another circle shaped sprite, or use something like the 3rd party canvas plugin to redraw it to a new image (not necessary if you don't actually need the user to download the image)
Hi Lof, thank for helping .
For masking check out "Blend modes.capx" in your construct2\examples directory.
I have used a mask over it however this will not let me see through to the layer behind.
ie if the player uploads the target as a tree when hit i want to see through the tree to the forest or what ever behind.