Less colourful pair drinking beer (5)
I believe the answer is:
paler
'less colourful' is the definition.
(I've seen this before)
'pair drinking beer' is the wordplay.
'pair' becomes 'pr' (abbreviation).
'drinking' is an insertion indicator (inserted letters are consumed or drunk).
'beer' becomes 'ale' (type of beer).
'pr' going around 'ale' is 'PALER'.
(Other definitions for paler that I've seen before include "Less colourful" , "comparatively anaemic" , "rather sickly-looking" , "Less dark" , "Lighter in colour" .)