Make it small as opposed to thick (8)

I believe the answer is:

condense

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'make it small' is the definition.
I can't tell whether this defines the answer.

'opposed to thick' is the wordplay.
'opposed' becomes 'con' (I've seen this in other clues).
'to thick' becomes 'dense' (synonyms).
'con'+'dense'='CONDENSE'

'as' is the link.

Can you help me to learn more?

(Other definitions for condense that I've seen before include "cut down" , "precis" , "Abridge" , "Summarise" , "Change from vapour to liquid" .)

I've seen this clue in the Evening Standard.

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