Heard bucket has little colour (4)
I believe the answer is:
pale
'little colour' is the definition.
'pale' can be an answer for 'colour' (I have seen 'Lacking colour ' mean 'pale' so perhaps 'colour' could also mean 'pale'). I'm not certain of the 'little' bit.
'heard bucket' is the wordplay.
'heard' shows a homophone (sound like).
'bucket' becomes 'pail' (synonyms).
'pail' sounds like 'PALE'.
'has' is the link.
Can you help me to learn more?
(Other definitions for pale that I've seen before include "Upright member" , "livid" , "beyond which one is out of line?" , "A bit of fencing" , "wooden post" .)