Owns different ammunition to pile up (8)
I believe the answer is:
snowball
'pile up' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'owns different ammunition' is the wordplay.
'different' indicates an anagram.
'ammunition' becomes 'ball' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'owns' anagrammed gives 'snow'.
'snow'+'ball'='SNOWBALL'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for snowball that I've seen before include "Quickly get bigger" , "Keep getting bigger" , "Increase rapidly in size - advocaat and lemonade" , "Cocktail made from lemonade and advocaat" , "Wintry missile - demonised by 17" .)