Ravel’s penned unusual Slav or Czech nationalist work (2,5)

'czech nationalist work' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'ravel's penned unusual slav' is the wordplay.
I cannot really understand how this works, but
an anagram of 'slav' is 'vlas' which is present in the answer.
The remaining letters 'mat' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

'or' is the link.

Can you help me to learn more?