Thus endlessly can provide shelter (3)
I believe the answer is:
hut
'shelter' is the definition.
(hut is a kind of shelter)
'thus endlessly can' is the wordplay.
'endlessly' means to remove the last letter.
'can' is an anagram indicator (I've seen 'canned' mean this (canned can mean drunk)).
'thus' with its last letter taken away is 'thu'.
'thu' with letters rearranged gives 'HUT'.
'provide' is the link.
(Other definitions for hut that I've seen before include "Small crudely-built shelter" , "Small roughly-made house or shelter" , "'Shack, hovel (3)'" , "Simple abode" , "Small, simple shelter" .)