It's put on conclusively, as cover (3)

I believe the answer is:

lid

I'm a little stuck... Click here to teach me more about this clue!

'cover' is the definition.
(I know that lid is a type of cover)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for lid that I've seen before include "Cover as for jar" , "Top crust of pie" , "Pie crust; cover" , "Receptacle cover" , "Cover for box or eye" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app