Just say no, it must be returned by the soldiers (7)
I believe the answer is:
mention
'just say' is the definition.
'mention' can be an answer for 'say' (mentioning is a kind of saying). I am not certain of the 'just' bit.
'no it must be returned by the soldiers' is the wordplay.
'must be returned' says the letters should be written backwards (letters sent back).
'by' says to put letters next to each other.
'the soldiers' becomes 'men' (men can mean a group of soldiers).
'no'+'it'='noit'
'noit' back-to-front is 'tion'.
'tion' put after 'men' is 'MENTION'.
Can you help me to learn more?
(Other definitions for mention that I've seen before include "Briefly refer to (something)" , "Allude to" , "Make reference to" , "Remark" , "Cite; quote" .)