Denial of strike from head: actual lines (8)
I believe the answer is:
rebuttal
'denial' is the definition.
(I've seen this before)
'strike from head actual lines' is the wordplay.
'strike from head' becomes 'butt' (a head butt).
'actual' becomes 'real' (similar in meaning).
'lines' indicates putting letters inside (line could historically mean to cover something).
'butt' going inside 'real' is 'REBUTTAL'.
'of' is the link.
(Other definitions for rebuttal that I've seen before include "Answer" , "A contradiction of evidence" , "resistance to attack" , "Denial" , "Disproof" .)