Perhaps sneaky hit from tennis player made them lose their grip on drink? (8)

I believe the answer is:

dropshot

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'perhaps sneaky hit from tennis player made them lose' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'grip on drink?' is the wordplay.
'grip on' becomes 'drop' (I can't explain this - if you can you should believe this answer much more).
'drink?' becomes 'shot' (I've seen this before).
'drop'+'shot'='DROPSHOT'

'their' acts as a link.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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