A blood-sucker gets the credit (4)
I believe the answer is:
tick
'credit' is the definition.
(I've seen this in other clues)
'a blood-sucker gets the' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'ick' 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 tick that I've seen before include "Objectionable person" , "Credit; clock sound" , "Blood-sucking mite or parasitic insect" , "Credit - bloodsucker" , "Credit; insect" .)