Complaint finds German not at home (4)
I believe the answer is:
gout
'complaint' is the definition.
(gout is a kind of disease)
'german not at home' is the wordplay.
'german' becomes 'g' (abbreviation).
'not at home' becomes 'out' (out can mean away from home).
'g'+'out'='GOUT'
'finds' acts as a link.
(Other definitions for gout that I've seen before include "Painful inflammation of feet - too much rich food" , "Painful inflammation of the foot" , "Disease causing pain in joints" , "Toe-inflammation disease" , "Painful ailment, often of the foot" .)