Socialists holding my data (7)
I believe the answer is:
records
'data' is the definition.
Although both the answer and definition are plural nouns, I can't see how one could define the other.
'socialists holding my' is the wordplay.
'socialists' becomes 'reds' (red is a kind of socialist).
'holding' is an insertion indicator.
'my' becomes 'cor' (both are expressions of surprise).
'reds' enclosing 'cor' is 'RECORDS'.
Can you help me to learn more?
(Other definitions for records that I've seen before include "Annotations of events" , "The best (or worst) performances ever" , "Makes written note" , "LPs, e.g." , "Files" .)