East German comes in ready to make swift reply (7)
I believe the answer is:
riposte
'swift reply' is the definition.
'riposte' can be an answer for 'reply' (riposte is a kind of reply). I am not certain of the 'swift' bit.
'east german comes in ready' is the wordplay.
'east german' becomes 'ost' ('east' in German).
'comes in' is an insertion indicator.
'ready' becomes 'ripe' (similar in meaning).
'ost' placed into 'ripe' is 'RIPOSTE'.
'to make' is the link.
Can you help me to learn more?
(Other definitions for riposte that I've seen before include "Poster I alter for repartee" , "Smart reply" , "Snappy comeback" , "Quick clever reply" , "Repartee; quick thrust (fencing)" .)