Germany is supported by moderate complaint (7)
I believe the answer is:
disease
'complaint' is the definition.
(I've seen this before)
'germany is supported by moderate' is the wordplay.
'germany' becomes 'd' (vehicle registration code for Deutschland).
'supported by' means one lot of letters go next to another (in a down clue, some letters hold up others).
'moderate' becomes 'ease' (I've seen this in another clue).
'd'+'is'+'ease'='DISEASE'
(Other definitions for disease that I've seen before include "affection" , "Ailment, malady" , "Illness, malady" , "Seaside (anag) -- ailment" , "Sickness" .)