Breaking rib in a hurry to improve image (8)
I believe the answer is:
airbrush
'to improve image' is the definition.
'breaking rib in a hurry' is the wordplay.
'breaking' indicates anagramming the letters (back).
'in' indicates putting letters inside.
'hurry' becomes 'rush' (synonyms).
'rib' anagrammed gives 'irb'.
'a'+'rush'='arush'
'irb' put into 'arush' is 'AIRBRUSH'.
(Other definitions for airbrush that I've seen before include "Prettify - alter a photo" , "It's used to enhance a photograph" , "conceal imperfections?" , "change photo?" , "paint over" .)