Historical river meadow (7)
I believe the answer is:
pasture
'meadow' is the definition.
(thesaurus)
'historical river' is the wordplay.
'historical' becomes 'past' ('past' can be similar in meaning to 'historical').
'river' becomes 'ure' (I have seen 'River of Wensleydale ' mean 'ure' so perhaps 'river' could also mean 'ure').
'past'+'ure'='PASTURE'
(Other definitions for pasture that I've seen before include "Land suitable for grazing" , "Meadowland" , "Grass for grazing" , "Stock holder, perhaps" , "Field suitable for grazing" .)