Shelter in a terrible emergency (3)
I believe the answer is:
lee
'shelter' is the definition.
(thesaurus)
'in a terrible emergency' is the wordplay.
'in' says the answer is hidden in the clue.
'LEE' is hidden in the letters of 'terrible emergency'.
(Other definitions for lee that I've seen before include "The sheltered side - of Cork's river?" , "Shelter" , "The side that's sheltered from the wind" , "The sheltered side of something" , "Towards the side away from the wind (naut)" .)