German girl has a job churning out copies of The Mirror (10)
I believe the answer is:
glassworks
'churning out copies of the mirror' is the definition.
I can't tell whether this defines the answer.
'german girl has a job' is the wordplay.
'german' becomes 'g' (abbreviation).
'girl' becomes 'lass' (lass is a kind of girl).
'has a job' becomes 'works' (I've seen this before).
'g'+'lass'+'works'='GLASSWORKS'
Can you help me to learn more?
(Other definitions for glassworks that I've seen before include "Factory making lights" , "some of whose output may be cut?" , "Manufacturer of, eg, windows" .)