Sea's inlets eroding main points (10)
I believe the answer is:
essentials
'main points' is the definition.
The answer and definition can be both natural objects as well as being plural nouns.
Maybe you can see an association between them that I can't see?
'sea's inlets eroding' is the wordplay.
'sea's inlets' can be anagrammed to 'ESSENTIALS'.
But, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for essentials that I've seen before include "necessities" , "Things needed" .)