Stay on border (6)
I believe the answer is:
reside
'stay' is the definition.
(thesaurus)
'on border' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'border' becomes 'side' (I can't justify this - if you can you should believe this answer much more).
're'+'side'='RESIDE'
Can you help me to learn more?
(Other definitions for reside that I've seen before include "Stay - desire (anag)" , "Live in permanently" , "Dwell permanently" , "Make one's home permanently" , "Dwell in desire" .)