Verruca (4)
I believe the answer is:
wart
'verruca' is the definition.
(I know that verruca can be written as wart)
This is the entire clue.
(Other definitions for wart that I've seen before include "Horny skin growth" , "Verruca" , "Small rounded protuberance on the skin" , "Abnormal blemish on the skin, caused by a virus" , "Charmable excrescence" .)