Rich, released from Further Education, revolutionised capacity (5)
I believe the answer is:
litre
'capacity' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for litre that I've seen before include "1.7598 UK pints" , "Metric measure of capacity" , "Metric liquid measure" , "Metric unit of volume" , "French volume" .)