Reticence? Keep it for future use (7)
I believe the answer is:
'reticence?' is the definition.
(I know that reticence can be written as reserve)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for reserve that I've seen before include "Husband - substitute" , "not in the front line" , "Book - substitute player" , "Modesty- store" , "ice" .)