While I'm not completely sure what type of burn it is. It is burn, Try letting up on the nutes a little bit. The leaf is not ruined, You only want to trim it off if it gets about 50% yellow.
That looks like newt burn to me. A light burn would be more towards the top of the plant and its only on the very ends so its most likely not light. I would just ease up on the newts a little bit and make sure your ph isnt out of wack.