Marked with dots, plans ultimately something to go on! (6)
I believe the answer is:
spotty
'marked' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for spotty that I've seen before include "Inconsistent" , "Teenagers are often so" , "Pimply or covered with dots" , "Maculate (like a leopard?)" , "Covered in rash" .)