Vulgar reason - something we share (6,6)

I believe the answer is:

common ground

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'something we share' is the definition.
I can't tell whether this defines the answer.

'vulgar reason' is the wordplay.
'vulgar' becomes 'common' (synonyms).
'reason' becomes 'ground' (synonyms).
'common'+'ground'='COMMON GROUND'

Can you help me to learn more?

(Other definitions for common ground that I've seen before include "Agreed basis in an argument" , "facilitates a start to negotiations" , "Public arena" , "Such land" , "Shared views" .)

I've seen this clue in The Daily Express.

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