Surgical tool, large, reshaped ears (5)
I believe the answer is:
laser
'surgical tool' is the definition.
(I've seen this in another clue)
'large reshaped ears' is the wordplay.
'large' becomes 'l' (eg in clothes sizes).
'reshaped' is an anagram indicator.
'ears' with letters rearranged gives 'aser'.
'l'+'aser'='LASER'
(Other definitions for laser that I've seen before include "Surgical device" , "Generator of beam" , "Device that generates an intense beam of light" , "Optical device producing an intense beam of light" , "light-intensifier" .)