Balls found when emptying older buildings (4)
I believe the answer is:
orbs
'balls' is the definition.
('orb' can be a synonym of 'ball')
'emptying older buildings' is the wordplay.
'emptying' suggests removing the centre.
'buildings' becomes 'bs' (I am not sure about this - if you are sure you should believe this answer much more).
'older' with its middle removed is 'or'.
'or'+'bs'='ORBS'
'found when' acts as a link.
Can you help me to learn more?
(Other definitions for orbs that I've seen before include "Spherical objects" , "Round objects" , "Poetic spheres or eyes" , "Eyeballs" , "Nices eyes, bros" .)