Protection from undesirable exposure (3)
I believe the answer is:
lee
'protection' is the definition.
(I've seen this in another clue)
'from undesirable exposure' is the wordplay.
'from' says the answer is hidden in the clue.
'LEE' is hidden in the letters of 'undesirable exposure'.
(Other definitions for lee that I've seen before include "The sheltered side of something" , "Confederate general" , "Area sheltered from the wind" , "Sheltered from the wind in Cork, perhaps" , "Shelter" .)