Improving new image recurring in Bond, initially discarded (2,3,4)
I believe the answer is:
on the mend
'improving' is the definition.
(on the mend means improving after an illness)
'new image recurring in bond initially discarded' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'image recurring' becomes 'theme' (theme can mean a recurring motif or image).
'in' indicates putting letters inside.
'initially discarded' means to remove the first letter (the initial letter is discarded).
'n'+'theme'='ntheme'
'bond' with its first letter taken away is 'ond'.
'ntheme' placed within 'ond' is 'ON THE MEND'.
(Other definitions for on the mend that I've seen before include "Looking up" , "Recovering from an injury or illness" , "undergoing recovery?" , "Improving in health" , "returning to health" .)