A colour of some importance (3)
I believe the answer is:
tan
'a colour' is the definition.
(I know that tan is a kind of colour)
'some importance' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'TAN' can be found hidden inside 'importance'.
'of' acts as a link.
(Other definitions for tan that I've seen before include "Sun-kissed" , "Acquire a sunburn" , "Turn dark in sun" , "Brown to beat" , "Prepare leather" .)