Upper classes missing top appearance (5)
I believe the answer is:
entry
'appearance' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'upper classes missing top' is the wordplay.
'upper classes' becomes 'gentry' (I've seen this before).
'missing top' means to remove the first letter.
'gentry' with its first letter taken off is 'ENTRY'.
Can you help me to learn more?
(Other definitions for entry that I've seen before include "Door, access" , "Opening" , "Item in an account book" , "Door; appearance" , "field" .)