Find empty library weird (9)
I believe the answer is:
unearthly
'weird' is the definition.
(I know that weird can be written as unearthly)
'find empty library' is the wordplay.
'find' becomes 'unearth' (unearthing is a kind of finding).
'empty' suggests removing the centre.
'library' with its middle removed is 'ly'.
'unearth'+'ly'='UNEARTHLY'
(Other definitions for unearthly that I've seen before include "could be weird" , "Disturbingly mysterious" , "Preposterous" , "Sunny" , "H G Wells's invaders appeared?" .)