Smears experts (4)
I believe the answer is:
dabs
I believe this clue is a double definition.
'smears' is the first definition.
'experts' is the second definition.
(I've seen this before)
(Other definitions for dabs that I've seen before include "Fish < experts" , "Fingerprints (slang)" , "fingerprint" , "Fingerprints (colloq.)" , "digitally recorded evidence" .)