Landowner endlessly seen in retreat (4)
I believe the answer is:
lair
'retreat' is the definition.
(thesaurus)
'landowner endlessly' is the wordplay.
'landowner' becomes 'laird' (Scottish term for a landowner).
'endlessly' means to remove the last letter.
'laird' with its last letter taken off is 'LAIR'.
'seen in' is the link.
(Other definitions for lair that I've seen before include "Rail about wild animal's home" , "enclosure" , "Supposed large ape, the Bigfoot" , "Den of a wild animal" , "Secret base" .)