Better half by England’s left back (7)
I believe the answer is:
espouse
'left back' is the definition.
'espouse' can be an answer for 'back' (espouse can mean to back or support). I'm unsure of the 'left' bit.
'better half by england's' is the wordplay.
'better half' becomes 'spouse' (I've seen this in another clue).
'by' is a charade indicator (letters next to each other).
'england' becomes 'E' (short for England).
'spouse' put after 'e' is 'ESPOUSE'.
Can you help me to learn more?
(Other definitions for espouse that I've seen before include "See opus (anag)" , "Adopt or support, say a cause" , "Adopt - give support to" , "Take in marriage" , "Give support to, say a cause" .)