Drag counter for ankle-biter? (4,5)

I believe the answer is:

puff adder

I'm a little stuck... Click here to teach me more about this clue!

'ankle-biter?' is the definition.
I can't tell whether this defines the answer.

'drag counter' is the wordplay.
'drag' becomes 'puff' (synonyms).
'counter' becomes 'adder' (someone who counts or adds up).
'puff'+'adder'='PUFF-ADDER'

'for' acts as a link.

Can you help me to learn more?

(Other definitions for puff adder that I've seen before include "Large viper" , "Snake" , "poisonous creeper" , "African viper" , "Poisonous type" .)

I've seen this clue in the Sydney Morning Herald.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.