Change some medical terminology (5)
I believe the answer is:
alter
'change' is the definition.
(I know that change can be written as alter)
'some medical terminology' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'ALTER' can be found hidden inside 'medical terminology'.
(Other definitions for alter that I've seen before include "Adapt" , "Alert to change" , "Revise" , "Bout of extravagant spending" , "Metamorphose" .)