A shock for the head! (3)
I believe the answer is:
mop
I believe this is a double definition.
'a shock' is the first definition.
(I've seen this before)
'head' is the second definition.
(I have seen 'head of hair' mean 'mop' so perhaps 'head' could also mean 'mop')
'for the' acts as a link.
(Other definitions for mop that I've seen before include "Bundle of soft material at end of stick for cleaning" , "Shock of hair; soak (up)" , "Swab" , "Cleaning implement" , "Hair, unkempt" .)