Colour lines somewhat regular (7)
I believe the answer is:
habitue
'regular' is the definition.
(I know that regular can be written as habitue)
'colour lines somewhat' is the wordplay.
'colour' becomes 'hue' (a hue is a colour or complexion).
'lines' indicates putting letters inside (line could historically mean to cover something).
'somewhat' becomes 'a bit' (a bit).
'hue' enclosing 'abit' is 'HABITUE'.
(Other definitions for habitue that I've seen before include "Frequent visitor to a place" , "One of the regulars" , "One who visits a place frequently 97)" , "Regular customer" , "Regular attendant" .)