Shoot nurse working to protect king (7)
I believe the answer is:
tendron
'shoot' is the definition.
(I've seen this before)
'nurse working to protect king' is the wordplay.
'nurse' becomes 'tend' (tend can mean to nurse or look after).
'working' becomes 'on' (e.g. a machine is working or on).
'to protect' indicates putting letters inside (inserted letters are held or protected).
'king' becomes 'R' (abbreviation of Latin rex).
'tend'+'on'='tendon'
'tendon' going around 'r' is 'TENDRON'.
(Another definition for tendron that I've seen is " Shoot".)