Princess seen on camera clearing lightspeed (4)
I believe the answer is:
leia
'princess' is the definition.
(Princess Leia in Star Wars)
'camera clearing lightspeed' is the wordplay.
'camera' becomes 'Leica' (brand of camera).
'clearing' indicates named letters should be taken away.
'lightspeed' becomes 'c' (c represents the speed of light).
'leica' with 'c' taken away is 'LEIA'.
'seen on' acts as a link.
(Other definitions for leia that I've seen before include "Revolutionary leader" , "Star Wars princess" .)