Against work at river area (8)

I believe the answer is:

opposite

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'against' is the definition.
(thesaurus)

'work at river area' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'at' says to put letters next to each other.
'river' becomes 'Po River' (Italian river).
'area' becomes 'site' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'op'+'po'+'site'='OPPOSITE'

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(Other definitions for opposite that I've seen before include "Facing - reverse" , "Facing on the other side" , "Contrary or face-to-face" , "Directly facing each other" , "Oppose it, being faced against" .)

I've seen this clue in The Hindu.

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