Mend part of shoe, did you say? (4)
I believe the answer is:
heal
'mend' is the definition.
('heal' can be a synonym of 'mend')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for heal that I've seen before include "Cure, make well" , "Cure, recover" , "remedy" , "Cure, mend" , "Cure, restore" .)