Colour of a magnate, perhaps (7)
I believe the answer is:
magenta
'colour' is the definition.
(magenta is a shade of purple)
'a magnate perhaps' is the wordplay.
'perhaps' is an anagram indicator.
'magnate' is an anagram of 'MAGENTA'.
'of' is the link.
(Other definitions for magenta that I've seen before include "Colourful" , "Shade of purple" , "Purplish-pink colour" , "Bright purplish-red" , "Colour named after a bloody 1859 battle in Italy" .)