To some trumpeters, it means 'Rock' (5)
I believe the answer is:
peter
'rock' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'to some trumpeters it' is the wordplay.
'to some' indicates the answer is hidden within the clue (some parts of the word are used).
'PETER' can be found hidden inside 'trumpeters it'.
'means' acts as a link.
Can you help me to learn more?
(Other definitions for peter that I've seen before include "Leader of the Apostles" , "Cephas" , "emperor" , "Rock-like apostle" , "Play high card before low" .)