Drop a trail of blood? (7)
I believe the answer is:
descent
'blood?' is the definition.
('descent' can be a synonym of 'blood')
'drop a trail' is the wordplay.
'drop' becomes 'de' (I am not sure about this - if you are sure you should believe this answer much more).
'a trail' becomes 'scent' (an animal's trail is its scent).
'de'+'scent'='DESCENT'
'of' is the link.
Can you help me to learn more?
(Other definitions for descent that I've seen before include "that concerns genealogist?" , "Drop" , "A climb down" , "Downward journey" , "Pedigree" .)