leaking mixer tap

[mjgh]

The single lever mixer tap in the WHB of my campervan is leaking following exposure to frost - no other damage
It is a Paini ,? Magnum or probably older version, at least 5 years old.
There is no apparent way to access the innards of the tap. How do I take it apart? is it likely to have a washer or a cartridge and is that likely to be the problem

 

[helpsy]

When you turn the tap from on to off is the handle turning through 90 degrees or does it turn a lot more than that?

 

[Plumbstar Tom]

single elver says to me its a cartridge

frost damage may mean new tap as well

is there a cap or indicator on the handle that pops off with a stanley blade

 

[mjgh]

tap is working perfectly except for leak

I can see no way to access the tap exce[pt to remove it from the basin - possible but very awkward due to space restriction in campervan