ADDER

• ... stingeth like an ___: Proverbs 23:32

• Abacus often

• Abacus operator

• Abacus user

• Abacus wielder

• Abacus, at times?

• Abacus, e.g.

• Accountant, often

• Bill checker

• Calculating person?

• Calculating reptile?

• Calculating snake?

• Calculator

• Calculator user

• Calculator, at times

• Calculator, often

• Columnist?

• Common viper

• CPA at work

• CPA, at times

• CPA, e.g.

• Crawler that causes dread

• Dangerous reptile

• Dangerous slitherer

• Dangerous snake

• Deadly snake

• Deadly viper

• Dread awful summer (5)

• European menace

• European viper

• Fer-de-lance's kin

• Figurehead?

• Harmless crawler

• He figures it's a serpent

• Hognose snake

• Hognose snake: puff ___

• Holmes' 'speckled band' was one

• Kind of snake

• Kind of viper

• Krait

• Lizard eater

• Math student

• Mathematical reptile?

• Mathematical snake?

• Milk snake

• Milk snake, e.g.

• Northern copperhead, for one

• Office machine

• Old World snake

• One doing simple math

• One doing sums

• One putting two and two together is less happy, left out (5)

• One working on a column

• Pocket calculator, e.g.

• Poisonous snake

• Puff ___

• Puff ___ (dangerous snake)

• Puff ___ (hognose snake)

• Puff follower

• Puff snake

• Puffed up snake

• Relative of a rattlesnake

• Reptile that's really sumthing?

• Scary snake

• Scotland's only poisonous snake

• Scotland's only snake

• Serpent

• Small snake

• Small viper

• Snake

• Snake also called the common viper

• Snake in the grass, perhaps

• Snake in the grass, really

• Snake or calculating person

• Snake or CPA

• Snake that counts?

• Snake that does sums?

• Snake that gets total results?

• Snake that's really sumthing?

• Snake to count on?

• Snake variety

• Snake with a puff variety

• Snake with venom

• Snaky CPA?

• Someone doing sums

• Sort of snake

• Sum finder

• Sum kind of snake?

• Sum seeker

• Summer

• Summer at the office

• Summer in the schoolroom

• Summer snake (5)

• Terrestrial viper

• The Black ___ (first of a Rowan Atkinson Britcom series)

• The common viper

• TV's 'The Black --'

• Type of snake

• Venomous reptile

• Venomous snake

• Venomous viper

• Viper

• Viper, and a clue to this puzzle's theme

• Small terrestrial viper common in northern Eurasia