Dye used to outline very small bone (5)
I believe the answer is:
anvil
'small bone' is the definition.
'dye used to outline very' is the wordplay.
I cannot really see how this works, but
'very' could be 'v' (common abbreviation) and 'v' is present in the answer.
'dye' could be 'anil' (anil is a kind of dye) and 'anil' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for anvil that I've seen before include "Alvin (anag.)" , "Block in smithy" , "One frequently gets hammered" , "A blacksmith's iron block" , "Block on which metal can be hammered" .)