Took part in parade, urged to protect commander (9)
I believe the answer is:
processed
'took part in parade' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Perhaps there's a link between them I don't understand?
'urged to protect commander' is the wordplay.
'urged' becomes 'pressed' ('press' can be a synonym of 'urge').
'to protect' indicates putting letters inside (inserted letters are held or protected).
'commander' becomes 'OC' (short for officer commanding).
'pressed' placed around 'oc' is 'PROCESSED'.
Can you help me to learn more?
(Other definitions for processed that I've seen before include "Put a product through a series of stages" , "Put something through a series of stages" , "Refined (of food)" , "Put something through a series of operations" , "Dealt with, moved things along" .)