do you think this tree is ded it turned brown a few weeks ago when it was hot, will it come back to life next year or do I have to take it down
It may well be dead But Keep an eye on it this year into next, it may well come back, but you can scrap a small bit of bark off the bottom of the trunk to see if it's green underneath, if it is leave it alone. Last winter we had a bit of rain and some thing's didn't survive and a lot of things drowned/or should I say there roots were under water for far to long and died back then the weather turned and it came out quite hot putting stress on the plant, with less root and all that heat something had to give and I think that is what happened in your case, so it might pull through X.
See what other people think, there are some bright sparks on the site.
What is (was) it?
and how long has it been there?
The flowering cherry tree in my front garden has dropped it leaves already. It was the really dry May,June and July we had, has stressed it. Leave it until spring to see if it terminal.