Dot revealed the purpose of base ten (7,5)
I believe the answer is:
decimal point
'base ten' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'dot revealed the purpose' is the wordplay.
I cannot quite understand how this works, but
'dot' could be 'point' (synonyms) and 'point' is located in the answer.
The remaining letters 'decimal' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for decimal point that I've seen before include "The dot in 10.67" , "What is in the middle of 1.5 and 2.5, say" , "It separates pounds from pence" , "I'm dot in place (anag)" , "Dot in a number" .)