Some policy analyst in blue (4)
I believe the answer is:
cyan
'blue' is the definition.
(I have seen 'Greenish blue ' mean 'cyan' so perhaps 'blue' could also mean 'cyan')
'some policy analyst in' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'CYAN' is hidden within 'policy analyst in'.
(Other definitions for cyan that I've seen before include "Primary blue colour in printing" , "Greenish-blue colour complementary to red" , "Printer's blue" , "Blue hue" , "Bluish-green" .)