Hyphenated in OED just as you see it here.

• 05.130 All at once there came a blood-curdling shriek,

“blood, n. (and int.).” OED Online. Oxford University Press, June 2017. Web. 5 September 2017.

OED gives the first mention of this game in 1600:

1600   S. Rowlands Letting of Humors Blood iv. 64   At hot-cockles, leape-frogge, or blindman-buffe.

Now I want to know how to play hot-cockles!

• 05.145 Then it was like a horrible game of blind-man’s-buff.

“blind-man’s-buff, n.” OED Online. Oxford University Press, June 2017. Web. 5 September 2017.

• 06.082 Other birds flew to the tree-tops
• 19.011 The wind’s in the tree-top, the wind’s in the heather;

Hyphenated or two words will do for OED.

“ˈtree-top | tree top, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/205437. Accessed 21 September 2017.

• 02.040 through the tree-trunks not far ahead.
• 02.079 it was thick as a young tree-trunk –
• 06.072 and brushwood round the tree-trunks.
• 07.045 propped on wooden posts made of single tree-trunks.
• 08.003 and scuttling behind tree-trunks.
• 08.109 of the branch nearest the tree-trunk

Hyphenated in its sub-entry in OED.

“tree, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/205416. Accessed 21 September 2017.