Shelter from fleet (3)
I believe the answer is:
lee
'shelter' is the definition.
(thesaurus)
'from fleet' is the wordplay.
'from' indicates a hidden word.
'LEE' is hidden in the letters of 'fleet'.
(Other definitions for lee that I've seen before include "The sheltered side of something" , "Shelter" , "actor" , "Robert E. - - , US hero" , "Bruce ___, martial arts ace" .)