They leave their coats on the wall (10)
I believe the answer is:
Here is my best explanation:
'they' is the definition.
Both the answer and definition are plural nouns.
Maybe there's a link between them I don't understand?
'their coats on the wall' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found within the answer.
'coats' could be 'plasters' (plastering is a kind of coating) and 'plasters' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
'leave' acts as a link.