Group One beginning to have change of heart (4)
I believe the answer is:
trio
'group' is the definition.
(a group of three)
'one beginning to have change of heart' is the wordplay.
'one beginning' says to take the initial letters.
'have' is a charade indicator (letters next to each other).
'change of heart' becomes 'rio' (I can't explain this - if you can you should believe this answer much more).
The initial letter of 'to' is 't'.
't'+'rio'='TRIO'
Can you help me to learn more?
(Other definitions for trio that I've seen before include "Ensemble musical piece, eg Beethoven's 'Archduke'" , "Beethoven's 'Archduke': famous piece written for this ensemble" , "Group of Magi?" , "Band of three" , "Group of three (musicians)" .)