Scoundrel, without finishing impetuous contact .. (6)
I believe the answer is:
rascal
'scoundrel' is the definition.
(I know that rascal is a type of scoundrel)
'without finishing impetuous contact' is the wordplay.
'without finishing' means to remove the last letter.
'impetuous' becomes 'rash' (I've seen this in another clue).
'contact' becomes 'cal' (I can't justify this - if you can you should believe this answer much more).
'rash' with its last letter removed is 'ras'.
'ras'+'cal'='RASCAL'
Can you help me to learn more?
(Other definitions for rascal that I've seen before include "Impudent child" , "Rogue of a lascar" , "Pickle" , "Mischievous person or confused lascar" , "Scallywag" .)