Adult sibling's current state (2,2)
I believe the answer is:
as is
'current state' is the definition.
(I've seen this before)
'adult sibling's' is the wordplay.
'adult' becomes 'a' (abbreviation).
'sibling' becomes 'sis' (short for sister).
'a'+'sis'='AS IS'
(Other definitions for as is that I've seen before include "In the existing circumstances" , "With no changes" , "in the present circumstances" , "not changed" , "unaltered" .)