Colours for party people (6)
I believe the answer is:
greens
I believe this clue is a double definition.
'colours' is the first definition.
(green is a kind of colour)
'party people' is the second definition.
(members of the Green Party)
'for' acts as a link.
(Other definitions for greens that I've seen before include "Veg" , "Political party" , "Vegetables and politicians of a certain hue" , "Leafy vegetables" , "Money" .)