Injure head in smacking roughly against article (6)
I believe the answer is:
scathe
'injure' is the definition.
(thesaurus)
'head in smacking roughly against article' is the wordplay.
'head in' says to take the initial letters.
'roughly' becomes 'ca'.
'against' means one lot of letters go next to another.
'article' becomes 'the' (the definite article in English).
The first letter of 'smacking' is 's'.
's'+'ca'+'the'='SCATHE'
(Other definitions for scathe that I've seen before include "To scorn" , "Harm, injure" , "Carpet" .)