Colour magazine regularly seen at bar (7)
I believe the answer is:
magenta
'colour' is the definition.
(magenta is a kind of colour)
'magazine regularly seen at bar' is the wordplay.
'magazine' becomes 'mag' (abbreviation for magazine).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'seen'+'at'+'bar'='seenatbar'
The alternate letters of 'seenatbar' are 'enta'.
'mag'+'enta'='MAGENTA'
(Other definitions for magenta that I've seen before include "Name tag (anag) - colour" , "Colourful" , "Light mauvish-crimson" , "Reddish-purple colour" , "Reddish purple" .)