Exploit prisoner associated with the German product that's been preserved for brewers to consume (4,6)

'product that's been preserved for brewers to consume' is the definition.
I can't tell whether this definition defines the answer.

'exploit prisoner associated with the german' is the wordplay.
'exploit' becomes 'milk' (to milk something is to exploit its potential).
'prisoner' becomes 'POW' (POW is an example).
'associated with' is a charade indicator (letters next to each other).
'the german' becomes 'der' ('the' in German).
'milk'+'pow'+'der'='MILK POWDER'

Can you help me to learn more?