Views welcoming the rise of Brown in legislative assemblies (7)

'legislative assemblies' is the definition.
(senate is a kind of legislative assembly)

'views welcoming the rise of brown' is the wordplay.
'views' becomes 'sees' ('see' can be a synonym of 'view').
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'the rise of' says the letters should be written in reverse.
'brown' becomes 'tan' (tan is a kind of brown).
'tan' in reverse letter order is 'nat'.
'sees' going around 'nat' is 'SENATES'.

'in' acts as a link.