Behold the donkey held in the rope with a noose (5)
I believe the answer is:
lasso
'noose' is the definition.
(I've seen this before)
'behold the donkey held in' is the wordplay.
'behold' becomes 'lo' (archaic exclamation meaning 'look!').
'the donkey' becomes 'ass' (ass is a term for a donkey).
'held in' is an insertion indicator.
'lo' enclosing 'ass' is 'LASSO'.
'the rope with a' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for lasso that I've seen before include "Rope used for catching cattle" , "Rope with noose for catching animals" , "Long-noosed rope" , "something to catch beast liable to run off" , "A cowboy's looped lariat" .)