Ryanair uses all the runway.

[EMIT]

Added definition of stopway

And the answer is ....
(EU OPS)
clearway’ means a defined rectangular area on the ground or water under the control of the appropriate authority, selected or prepared as a suitable area over which an aeroplane may make a portion of its initial climb to a specified height;

And about braking index of grass .......
accelerate-stop distance available (ASDA)’ means the length of the take-off run available plus the length of stopway, if such stopway is declared available by the State of the aerodrome and is capable of bearing the mass of the aeroplane under the prevailing operating conditions;

..and where I have written EU OPS, of course it is now EASA Ops, full title of the literary masterpiece is Regulation (EU) 965/2012 on air operations.