Witty response from Republican that is passed round office (7)
I believe the answer is:
riposte
'witty response' is the definition.
(riposte can mean a witty answer)
'republican that is passed round office' is the wordplay.
'republican' becomes 'r' (abbreviation).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'passed round' indicates putting letters inside.
'office' becomes 'post' (both can mean a position or job).
'ie' placed around 'post' is 'iposte'.
'r'+'iposte'='RIPOSTE'
'from' is the link.
(Other definitions for riposte that I've seen before include "Smart reply" , "Poster I alter for repartee" , "Fencer's counterattack" , "Reply, retort" , "Quick answer" .)