Initially short hair with highlights (8)
I believe the answer is:
stresses
'highlights' is the definition.
(I've seen this in another clue)
'initially short hair' is the wordplay.
'initially' indicates taking the first letters.
'hair' becomes 'tresses' (tresses are locks of hair).
The initial letter of 'short' is 's'.
's'+'tresses'='STRESSES'
'with' acts as a link.
(Other definitions for stresses that I've seen before include "Pressures or tensions" , "Puts pressure on" , "Lays emphasis on" .)