Rush around the fields, having been set free (8)
I believe the answer is:
released
'set free' is the definition.
(I've seen this before)
'rush around the fields' is the wordplay.
'rush' becomes 'reed' (plants found by water).
'around' indicates putting letters inside.
'the fields' becomes 'leas' (lea can mean a field or meadow).
'reed' enclosing 'leas' is 'RELEASED'.
'having been' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for released that I've seen before include "Set free" , "Freed from confinement" , "free after imprisonment?" , "Liberated" , "Let out - let out again" .)