Prepare for a rainy day (4)
'prepare for a rainy day' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for save that I've seen before include "Rescue from harm" , "Hang on to" , "Set aside" , "Spend less" , "what prevents a goal" .)
(Other definitions for hoard that I've seen before include "Amass and store privately" , "Stash of treasure" , "(Miser's) store" , "One's savings" , "Accumulated store" .)