A new way of composing letters (7)
I believe the answer is:
anagram
'way of composing letters' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'a new' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for anagram that I've seen before include "One way to clue" , "Rearrangement of letters in word or phrase to form another" , "Word rearranging another's letters" , "Jumbling of letters" , "Word that rearranges another's letters" .)