Regiment in the end finds wild myth initially hard to beat (6)
I believe the answer is:
rhythm
'beat' is the definition.
('rhythm' can be a synonym of 'beat')
'regiment in the end finds wild myth initially hard' is the wordplay.
'regiment in the end finds' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'wild' is an anagram indicator.
'initially' says to put letters next to each other.
'hard' becomes 'h'.
'myth' with letters rearranged gives 'ythm'.
'ythm' after 'h' is 'hythm'.
'r'+'hythm'='RHYTHM'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for rhythm that I've seen before include "Musical tempo or beat" , "Regular occurrence of stresses, pulse, etc" , "Cycle -- cadence" , "Beat - time - metre" , "Regular succession of sounds" .)