Equality initially introduced in political organisation (6)
I believe the answer is:
parity
'equality' is the definition.
(parity is a kind of equality)
'initially introduced in political organisation' is the wordplay.
'initially' suggests taking the first letters.
'in' indicates putting letters inside.
'political organisation' becomes 'party' (I've seen this before).
The initial letter of 'introduced' is 'i'.
'i' going within 'party' is 'PARITY'.
(Other definitions for parity that I've seen before include "Equality in status" , "equal treatment" , "state of equality" , "Beginner" , "Correspondence" .)