Bloodsucking rat is a blur in photo (9)
I believe the answer is:
parasitic
'bloodsucking' is the definition.
(I know that bloodsucking can be written as parasitic)
'rat is a blur in photo' is the wordplay.
'blur' is an anagram indicator (blur can mean a confusion or mess).
'in' indicates putting letters inside.
'photo' becomes 'pic' (short for picture).
'rat'+'is'+'a'='ratisa'
'ratisa' is an anagram of 'arasit'.
'arasit' put into 'pic' is 'PARASITIC'.
(Other definitions for parasitic that I've seen before include "Having food provided by host" , "like a leech" , "Living at another creature's expense" , "Living at the expense of the host organism" , "to be paid for by someone else" .)