Experienced, and German therefore nets half (9)
I believe the answer is:
undergone
'experienced' is the definition.
('undergo' can be a synonym of 'experience')
'and german therefore nets half' is the wordplay.
'and german' becomes 'und' ('and' in German).
'therefore' becomes 'ergo' (I've seen this before).
'half' means to take half the letters.
'nets' with half the letters taken is 'ne'.
'und'+'ergo'+'ne'='UNDERGONE'
(Other definitions for undergone that I've seen before include "Endured" , "Experienced" , "Suffered" , "sustained" .)