Susceptible to sunburn (4)
I believe the answer is:
pale
'susceptible to sunburn' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pale that I've seen before include "Having less colour than normal" , "livid" , "Light in colour" , "Very light coloured" , "It's unacceptable to go beyond this" .)