Communists seizing my chronicles (7)
I believe the answer is:
records
'chronicles' is the definition.
'communists seizing my' is the wordplay.
'communists' becomes 'reds' (red is a kind of communist).
'seizing' is an insertion indicator (inserted letters are seized).
'my' becomes 'cor' (both are expressions of surprise).
'reds' going around 'cor' is 'RECORDS'.
(Other definitions for records that I've seen before include "Discs" , "Archives" , "LPs, e.g." , "The best (or worst) performances ever" , "unsurpassed performances" .)