Order given to soldiers to show care (9)
I believe the answer is:
attention
'care' is the definition.
(synonyms)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for attention that I've seen before include "Applying the mind, mental concentration" , "Vigilance; care" , "Applicaton, concentration" , "Keen students pay this" , "What students must pay" .)