Headline penned by journalist, arresting (4)
I believe the answer is:
star
'headline' is the definition.
(I've seen this in another clue)
'penned by journalist arresting' is the wordplay.
'penned by' says the answer is hidden in the clue.
'STAR' is hidden within 'journalist arresting'.
(Other definitions for star that I've seen before include "Play a leading role" , "Pointed symbol" , "Celestial point of light" , "appear above others?" , "Lead actor" .)