Star needs massage — result of overexposure (9)
I believe the answer is:
sunstroke
'result of overexposure' is the definition.
'star needs massage' is the wordplay.
'star' becomes 'sun' (Sun is an example).
'needs' is a charade indicator (letters next to each other).
'massage' becomes 'stroke'.
'sun'+'stroke'='SUNSTROKE'
(Other definitions for sunstroke that I've seen before include "illness out of the blue" , "Hot summer day ailment" , "Problem caused by too much solar exposure" , "Illness incurred in trying for tan?" , "Ailment from spending too long tanning" .)