Glaring relative in residence (8)
I believe the answer is:
flagrant
'glaring' is the definition.
(I know that glaring can be written as flagrant)
'relative in residence' is the wordplay.
'relative' becomes 'gran' (short for grandmother).
'in' means one lot of letters goes inside another.
'residence' becomes 'flat' (I've seen this before).
'gran' going into 'flat' is 'FLAGRANT'.
(Other definitions for flagrant that I've seen before include "notorious" , "Shocking" , "Unashamed" , "Being shameless" , "Conspicuous, blatant" .)