Perhaps loosen carpet round top of stairs and take pile down (7)

'down' is the definition.
Both the answer and definition are adjectives.
Perhaps there's an association between them I don't understand?

'perhaps loosen carpet round top of stairs and take pile' is the wordplay.
I cannot quite see how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
'pile' could be 'stack' (synonyms) and 'stack' is present in the answer.
A single letter 'u' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?