What post-graduates work for, to a greater extent? (6,6)

I believe the answer is:

higher degree

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'what post-graduates work for' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'greater extent?' is the wordplay.
'greater' becomes 'higher' ('high' can be similar in meaning to 'great').
'extent?' becomes 'degree' (extent is a kind of degree).
'higher'+'degree'='HIGHER DEGREE'

'to a' acts as a link.

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I've seen this clue in The Globe and Mail.

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