Millstones round one's neck? (4)
I believe the answer is:
ties
'millstones' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'round one's neck?' is the wordplay.
'round' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'neck?' becomes 'tes' (I can't explain this - if you can you should give a lot more credence to this answer).
'i' going inside 'tes' is 'TIES'.
Can you help me to learn more?
(Other definitions for ties that I've seen before include "Items of neckwear" , "Connects" , "obligations" , "allegiances" , "Drawn games" .)