Written down like the two in water, symbolically (9)
I believe the answer is:
subscript
'written' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for subscript that I've seen before include "writing this below the line" , "It's written below and beside another character" , "It's written below the line" .)