Batter and crumble that covers over (4)
I believe the answer is:
root
'batter' is the definition.
The definition and answer can be both related to change as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
'crumble that covers over' is the wordplay.
'crumble' becomes 'rot' (I've seen this before).
'that covers' indicates putting letters inside.
'over' becomes 'o' (cricket abbreviation).
'rot' going around 'o' is 'ROOT'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for root that I've seen before include "essential nature" , "Turn up with the snout." , "burrow" , "Organ that anchors plants in the ground" , "Basic cause or origin" .)