Stray is pale with colour coming back (6)
I believe the answer is:
wander
'stray' is the definition.
(I know that stray can be written as wander)
'pale with colour coming back' is the wordplay.
'pale' becomes 'wan' (wan can mean pale or grey).
'with' is a charade indicator (letters next to each other).
'colour' becomes 'red' (red is a kind of colour).
'coming back' says the letters should be written in reverse.
'red' in reverse letter order is 'der'.
'wan'+'der'='WANDER'
'is' acts as a link.
(Other definitions for wander that I've seen before include "Roam around aimlessly" , "endless travel" , "Stroll" , "Go astray" , "Go to and fro" .)