Two-thirds of armies busy acquiring metal rifle (7)
I believe the answer is:
martini
'rifle' is the definition.
(I've seen this before)
'two-thirds of armies busy acquiring metal' is the wordplay.
I cannot really see how this works, but
'metal' could be 'ti' (Ti is an example) and 'ti' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for martini that I've seen before include "Cocktail made with gin or vodka and vermouth" , "In glass, one's dry" , "Cocktail of gin and dry vermouth" , "alcoholic drink" , "obtained from a bottle" .)