Getting better, continuously swallowing them (2,3,4)
I believe the answer is:
on the mend
'getting better' is the definition.
(on the mend means recovering from illness)
'continuously swallowing them' is the wordplay.
'continuously' becomes 'on end' (I've seen this in another clue).
'swallowing' indicates putting letters inside.
'onend' enclosing 'them' is 'ON THE MEND'.
(Other definitions for on the mend that I've seen before include "returning to health" , "undergoing recovery?" , "convalescing" , "Recovering from an injury or illness" , "Improving in health" .)