Crossword Genius

Did suit check, even by itself? (7)

Ross

I believe the answer is:

squared

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

'did' is the definition.
The answer and definition can be both to do with motion as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for squared that I've seen before include "Brought into accord" , "Agreed" , "Reconciled < , or bribed" , "Multiplied by itself" , "As four is to make 16" .)

I've seen this clue in The Telegraph.
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