In real estate, just in case (4)
I believe the answer is:
lest
'just in case' is the definition.
(I've seen this in another clue)
'in real estate' is the wordplay.
'in' indicates a hidden word.
'LEST' is hidden within 'real estate'.
(Other definitions for lest that I've seen before include "In order not to, to avoid the risk that" , "For fear that; in order to prevent" , "For fear that (something should happen)" , "For fear that (something happens)" , "In case" .)