Ready to support German complaint (5)
I believe the answer is:
'complaint' is the definition.
(an objection or source of annoyance)
'ready to support german' is the wordplay.
'ready' becomes 'ripe' (similar in meaning).
'to support' says to put letters next to each other (in a down clue, some letters hold up others).
'german' becomes 'g' (abbreviation).
'ripe' after 'g' is 'GRIPE'.
(Other definitions for gripe that I've seen before include "Grumble informally" , "Protest" , "Grievance" , "carp" , "Keep on complaining" .)