A little dust detectable during inspection (5)
I believe the answer is:
speck
'a little' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for speck that I've seen before include "Small mark" , "Tiny spot" , "Dot" , "Italian ham" , "Bit of dust" .)