Poet's key verse essentially (5)
I believe the answer is:
homer
'poet's' is the definition.
(Homer is an example)
'key verse essentially' is the wordplay.
'key' becomes 'home' (I can't explain this - if you can you should believe this answer much more).
'essentially' means to look at the middle letters.
The central letter of 'verse' is 'r'.
'home'+'r'='HOMER'
Can you help me to learn more?
(Other definitions for homer that I've seen before include "Greek author; pigeon" , "Trained pigeon" , "trained to get back to house" , "Great Greek poet of the Iliad and the Odyssey" , "successful run in America?" .)