Devour pig's tail in blood (5)
I believe the answer is:
gorge
'devour' is the definition.
(I've seen this before)
'pig's tail in blood' is the wordplay.
'tail' indicates one should take the final letters.
'in' means one lot of letters goes inside another.
'blood' becomes 'gore' ('gore' can be a synonym of 'blood'**).
The last letter of 'pig' is 'g'.
'g' inserted inside 'gore' is 'GORGE'.
(Other definitions for gorge that I've seen before include "Chasm; overeat" , "Eat too much" , "Devour" , "Deep valley" , "Overindulge" .)