Correspondence still centrally stored by company (6)
I believe the answer is:
parity
'correspondence' is the definition.
(I've seen this before)
'still centrally stored by company' is the wordplay.
'centrally' indicates the central letters.
'stored by' means one lot of letters goes inside another.
'company' becomes 'party' (both can mean a group of people).
The central letter of 'still' is 'i'.
'i' put within 'party' is 'PARITY'.
(Other definitions for parity that I've seen before include "Equal status or pay" , "Egalitarian goal" , "Equality in status" , "Equal condition" , "Correspondence" .)