HAVERHILL — Authorities say a 60-year-old man clearing debris left by recent storms has been struck and killed by a tree.A spokeswoman for the Essex district attorney tells The Eagle-Tribune the Haverhill man was working with his adult son at about 5 p.m. Sunday, cutting up a tree that had fallen during one of last month's storms.The tree he was cutting was leaning against another tree, which gave way and fell on him, pinning him to the ground.