European definition...
Where did you find that 2s? I don't doubt it's in some EU regulation.
I agree the issue is debatable and somewhat academic.
Neither ICAO Annex 11 nor PANS-ATM define "clearance". Annex 11 does say:
3.7.1 Contents of clearances
3.7.1.1 An air traffic control clearance shall indicate:
a) aircraft identification as shown in the flight plan;
b) clearance limit;
c) route of flight;
d) level(s) of flight for the entire route or part thereof and changes of levels if required;
e) any necessary instructions or information on other matters such as approach or departure manoeuvres, communications and the time of expiry of the clearance.
I would argue that "permission granted" does not meet the spirit of this, but then neither do most of the other "clearances" used in the UK.