Getting better (2,3,4)
'getting better' is the definition.
(on the mend means recovering from illness)
This is the entire clue.
(Other definitions for on the mend that I've seen before include "Improving in health" , "convalescing" , "Recovering from an injury or illness" , "returning to health" , "undergoing recovery?" .)
'getting better' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for improving that I've seen before include "Getting better" , "Recovering" , "Making better" .)