Ropes fence off to keep an eye on composure (8,2,4)
I believe the answer is:
presence of mind
'composure' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'ropes fence off to keep an eye' is the wordplay.
'off' is an anagram indicator.
'to keep an eye' becomes 'mind' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ropes'+'fence'='ropesfence'
'ropesfence' anagrammed gives 'presenceof'.
'presenceof'+'mind'='PRESENCE OF MIND'
'on' acts as a link.
Can you help me to learn more?
(Other definitions for presence of mind that I've seen before include "Wits are required to display such" , "alertness in crisis" .)