Showing marked contrast when freed from tension (2,6)

I believe the answer is:

in relief

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'showing marked contrast when freed' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'from tension' is the wordplay.
'from' becomes 'in' (I've seen this in other clues).
'tension' becomes 'relief' (I am not sure about this - if you are sure you should believe this answer much more).
'in'+'relief'='IN RELIEF'

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I've seen this clue in The Irish Independent.

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