One million standing for unwelcome burden (10)
I believe the answer is:
imposition
'unwelcome burden' is the definition.
'imposition' can be an answer for 'burden' (imposition is a kind of burden). I am not sure about the 'unwelcome' bit.
'one million standing' is the wordplay.
'one million' becomes 'im' (resembles 1m).
'standing' becomes 'position' (standing can mean one's position or status).
'im'+'position'='IMPOSITION'
'for' is the link.
Can you help me to learn more?
(Other definitions for imposition that I've seen before include "Unwelcome demand or burden" , "tax" .)