Insects foremost in carrying disease (8)
I believe the answer is:
crickets
'insects' is the definition.
(cricket is a type of insect)
'foremost in carrying disease' is the wordplay.
I cannot really see how this works, but
'disease' could be 'rickets' (rickets is a kind of disease) and 'rickets' is located in the answer.
A single letter 'c' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for crickets that I've seen before include "Chirping insects" , "They are chirpy" , "Noisy insects" , "Insects that chirp in chimneys" .)