Looks like a Phormium to me. You could trim some of the outer leaves back but I would sooner create a circular area of bare soil around it to make it look neater. It would also not be competing with the grass for nutrients.

Hi, welcome to GoY, I agree with Jimmy, Phormium, possibly Phormium tenax variegatum, Derek.

Thanks Jimmy and Derek - it's good to know what I'm looking at!
I will get shaping the ground underneath.