Start removing lid (7)
I believe the answer is:
opening
'lid' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'start removing' is the wordplay.
'start' becomes 'open' (opening is a kind of starting).
'removing' becomes 'ing' (I can't explain this - if you can you should give a lot more credence to this answer).
'open'+'ing'='OPENING'
Can you help me to learn more?
(Other definitions for opening that I've seen before include "Inauguration" , "First -- beginning" , "Aperture or first night" , "Initial" , "break" .)