Disinfectant target (4)
I believe the answer is:
germ
'disinfectant target' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for germ that I've seen before include "Microorganism causing disease" , "Cause of disease" , "Minute life form" , "tiny life form" , "Cause of infection" .)