It will draw blood (5)
I believe the answer is:
leech
'draw blood' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'it will' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
The remaining letters 'lech' is a valid word 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 leech that I've seen before include "Sucking parasite" , "Small worm once used for blood-letting, or a parasitical person" , "Worm - sponger" , "Clinging type" , "Medicinal bloodsucker" .)