It was used to press home a charge (6)
I believe the answer is:
ramrod
'it was used to press home a' is the definition.
The definition suggests a singular noun which matches the answer.
'charge' is the wordplay.
I cannot really see how this works, but
'charge' could be 'ram' (I've seen this in other clues) and 'ram' is present in the answer.
The remaining letters 'rod' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ramrod that I've seen before include "Gun cleaner, proverbially stiff and straight" , "Strict disciplinarian" , "Someone stern and inflexible - it was used with a musket" , "Pole for pushing charge into a gun barrel" , "Device for charging gun, proverbially stiff" .)