Ready to receive East German response (7)
I believe the answer is:
Here is my best explanation:
'response' is the definition.
(riposte is a kind of response)
'ready to receive east german' is the wordplay.
'ready' becomes 'ripe' ('ripe' can be similar in meaning to 'ready').
'to receive' is an insertion indicator.
'east german' becomes 'ost' ('east' in German).
'ripe' placed around 'ost' is 'RIPOSTE'.
(Other definitions for riposte that I've seen before include "Sharp answer", "Retort", "Smart reply", "Quick retort or return hit in fencing", "Witty comeback", "Witty reply", "Witty retort", "Repartee; quick thrust (fencing)", "Sharp reply" and "A quick or sharp reply".)