Summon for a drink before allowing to practise law? (4,2,3,3)

I believe the answer is:

call to the bar

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'to practise law?' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'summon for a drink before' is the wordplay.
'summon' becomes 'call' (I've seen this in another clue).
'for' becomes 'to' (eg both can mean 'in the opinion of').
'a drink before' becomes 'thebar' (I can't explain this - if you can you should believe this answer much more).
'call'+'to'+'thebar'='CALL TO THE BAR'

'allowing' acts as a link.

Can you help me to learn more?

I've seen this clue in The Irish News.

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