US financier set up — keeps playing a blinder (10)

'us financier' is the definition.
(19th-century financier William Henry Vanderbilt)

'set up keeps playing a blinder' is the wordplay.
'set' becomes 'tv' (TV set).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'keeps' indicates putting letters inside.
'playing' indicates anagramming the letters.
'tv' backwards is 'vt'.
'a'+'blinder'='ablinder'
'ablinder' anagrammed gives 'anderbil'.
'vt' placed around 'anderbil' is 'VANDERBILT'.