Crossword puzzle clue "joke targets at times"

NERD, a person obsessed with computers at the expense of human interaction, also NURD

a thin, crisp biscuit

BUTT, to hit with the head

a tree of genus Castanea, esp. the Spanish or sweet chestnut; its edible nut, also CHESNUT

ANT, a small industrious insect

NAPE, to attack with napalm