Area gripped by unknown criminal disposing of dead lout (5)
I believe the answer is:
yahoo
'lout' is the definition.
(I've seen this before)
'area gripped by unknown criminal' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'gripped by' is an insertion indicator.
'unknown' becomes 'y' (algebra).
'criminal' becomes 'hoo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'y'+'hoo'='yhoo'
'a' going into 'yhoo' is 'YAHOO'.
'disposing of dead' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for yahoo that I've seen before include "expression of delight" , "Rude, brutish type" , "Race of brutes in Gulliver's Travels" , "A Swiftian lout" , "[WHOOPEE] !" .)