Managed to hide old colour (4)
I believe the answer is:
roan
'colour' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I can't see?
'managed to hide old' is the wordplay.
'managed' becomes 'ran' (I've seen this before).
'to hide' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'ran' enclosing 'o' is 'ROAN'.
Can you help me to learn more?
(Other definitions for roan that I've seen before include "Horse with a coat of mixed colour" , "(Horse) white-sprinkled coat" , "Type of 17's coat colouring" , "Horse with reddish-brown coat" , "Bay spotted" .)