Very little work required to propel oneself through the water (6)

I believe the answer is:

stroke

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

'very little work' is the definition.
'stroke' can be an answer for 'work' (thesaurus). I'm unsure of the 'very little' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for stroke that I've seen before include "Caress; cricket shot" , "Rub gently" , "Member of rowing crew" , "beat?" , "Stoker (anag.)" .)

I've seen this clue in the Evening Standard.

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