Little bone found in custard topping (5)
I believe the answer is:
incus
'little bone' is the definition.
'incus' can be an answer for 'bone' (I've seen this before). I'm not sure about the 'little' bit.
'in custard topping' is the wordplay.
I cannot quite see how this works, but
'in' is within the answer.
This explanation may well be incorrect...
'found' acts as a link.
Can you help me to learn more?
(Other definitions for incus that I've seen before include "Hard part of the Listener" , "anvil (so we hear)" , "Bone in the middle ear" , "part of sound system" , "Middle-ear bone" .)