Hateful mother with capacity to conceal name (8)
I believe the answer is:
damnable
'hateful' is the definition.
(thesaurus)
'mother with capacity to conceal name' is the wordplay.
'mother' becomes 'dam' (female parent of an animal).
'with capacity' becomes 'able'.
'to conceal' indicates putting letters inside.
'name' becomes 'n' (common abbreviation e.g. on forms).
'dam'+'able'='damable'
'damable' going around 'n' is 'DAMNABLE'.
(Other definitions for damnable that I've seen before include "Execrable" , "really bad" , "Awful" , "Atrocious, infernal" , "Pernicious" .)