Shack gets new search (4)
I believe the answer is:
hunt
'search' is the definition.
('hunt' can be a synonym of 'search')
'shack gets new' is the wordplay.
'shack' becomes 'hut' ('hut' can be a synonym of 'shack').
'gets' is an insertion indicator (gets can mean captures or absorbs).
'new' becomes 'n'.
'hut' enclosing 'n' is 'HUNT'.
(Other definitions for hunt that I've seen before include "Quest" , "Pursue game" , "Search; pursue and kill" , "Organised search" , "Search for (prey)" .)