Core planet where the last shall be first (5)
I believe the answer is:
heart
'core planet' is the definition.
'heart' can be an answer for 'core' (I've seen this in another clue). I'm not certain of the 'planet' bit.
'the last shall be first' is the wordplay.
'the last' becomes 't' (I've seen this in other clues).
'shall' becomes 'hear' (I am not sure about this - if you are sure you should believe this answer much more).
'be first' says to put letters next to each other.
't' put after 'hear' is 'HEART'.
'where' acts as a link.
Can you help me to learn more?
(Other definitions for heart that I've seen before include "Vital part" , "Muscular organ for blood circulation" , "Muscular organ - compassion" , "Core, courage" , "Body organ" .)