Rowdy lout initially stabbing poet with little hesitation (7)
I believe the answer is:
hoodlum
'rowdy' is the definition.
(both can mean a troublemaker)
'lout initially stabbing poet with little hesitation' is the wordplay.
'initially' indicates taking the first letters.
'stabbing' means one lot of letters goes inside another (some letters stab themselves into others).
'poet' becomes 'hood' (I've seen this in other clues).
'with' means one lot of letters go next to another.
'little hesitation' becomes 'um'.
The initial letter of 'lout' is 'l'.
'hood'+'um'='hoodum'
'l' placed inside 'hoodum' is 'HOODLUM'.
(Other definitions for hoodlum that I've seen before include "Mobster" , "Tearaway" , "Lawless youth" , "One breaks the law" , "Hooligan" .)