Puts great pressure on clasps (7)

I believe the answer is:

strains

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'puts great' is the definition.
I can't tell whether this definition defines the answer.

'pressure on clasps' is the wordplay.
'pressure' becomes 'strain' (I've seen this before).
'on clasps' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'strain'+'s'='STRAINS'

Can you help me to learn more?

(Other definitions for strains that I've seen before include "Stresses and - -" , "Tries very hard" , "Melodies" .)

I've seen this clue in the Evening Standard.

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