Alexander VIII of Germany in wind-powered vehicle (4,5)
I believe the answer is:
sand yacht
'germany in wind-powered vehicle' is the definition.
I can't tell whether this definition defines the answer.
'alexander viii' is the wordplay.
'alexander' becomes 'Sandy' (nickname for Alexander).
'viii' becomes 'acht' (I can't explain this - if you can you should give a lot more credence to this answer).
'sandy'+'acht'='SAND-YACHT'
'of' is the link.
Can you help me to learn more?
(Another definition for sand yacht that I've seen is " Vessel at beach".)