Flower on top of hill, characteristic of Eire (5)
I believe the answer is:
irish
'characteristic of eire' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'flower on top of hill' is the wordplay.
'flower' becomes 'iris' (iris is a type of flower).
'on top of' says to take the initial letters.
The first letter of 'hill' is 'h'.
'iris'+'h'='IRISH'
Can you help me to learn more?
(Other definitions for irish that I've seen before include "Like Wilde or Yeats" , "Hibernian -- breed of 4" , "A people, language and whiskey" , "From Galway, say" , "From Eire" .)