Make sure friends achieve winning positions (10)

I believe the answer is:

checkmates

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

'achieve winning positions' is the definition.
I can't judge whether this definition defines the answer.

'make sure friends' is the wordplay.
'make sure' becomes 'check' (synonyms).
'friends' becomes 'mates' (mate is a kind of friend).
'check'+'mates'='CHECKMATES'

Can you help me to learn more?

(Other definitions for checkmates that I've seen before include "Finishes game (chess)" , "utter defeats" .)

I've seen this clue in The Daily Express.

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