Crossword Genius

Such a bottle best given to person employed in prison (8)

Ross

I believe the answer is:

screwtop

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

'person employed in prison' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'such a bottle best given' is the wordplay.
'such a bottle' becomes 'screw' (I can't justify this - if you can you should believe this answer much more).
'best' becomes 'top' (top can mean the very best).
'given' says to put letters next to each other.
'screw'+'top'='SCREWTOP'

'to' acts as a link.

Can you help me to learn more?

(Other definitions for screwtop that I've seen before include "one goes on the bottle" , "that closes jar" , "Describing a type of bottle" , "cap or lid" , "kind of bottle" .)

I've seen this clue in The Telegraph.
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