Enjoying popularity, like old colour (6)
I believe the answer is:
indigo
'colour' is the definition.
(indigo is a kind of colour)
'enjoying popularity like old' is the wordplay.
'enjoying popularity' becomes 'in'.
'like' becomes 'dig' (I've seen this in other clues).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'in'+'dig'+'o'='INDIGO'
(Other definitions for indigo that I've seen before include "Mood - (Duke Ellington)" , "supplier of blue stuff" , "Blue-violet colour" , "Sixth rainbow colour" , "product of woad" .)