Playwright with point about river and wasteland (10)
I believe the answer is:
wilderness
'wasteland' is the definition.
(thesaurus)
'playwright with point' is the wordplay.
'playwright with' becomes 'wilder' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'point' becomes 'ness' (ness can mean a geographical point).
'wilder'+'ness'='WILDERNESS'
'about river and' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for wilderness that I've seen before include "for a time unrecognised" , "Inhospitable region" .)