Correct helper is most important (5-4)
I believe the answer is:
right-hand
'is most important' is the definition.
I can't judge whether this defines the answer.
'correct helper' is the wordplay.
'correct' becomes 'right' (right can mean correct).
'helper' becomes 'hand' (I've seen this in another clue).
'right'+'hand'='RIGHT-HAND'
Can you help me to learn more?
(Other definitions for right-hand that I've seen before include "drive in a British vehicle" , "Principally relied on such" .)