Dog buried in obscurity (3)
I believe the answer is:
cur
'dog' is the definition.
(a cur is an aggressive or scruffy dog)
'buried in obscurity' is the wordplay.
'buried in' indicates a hidden word.
'CUR' is hidden within 'obscurity'.
(Other definitions for cur that I've seen before include "Vicious dog" , "Base fellow" , "Useless dog" , "Inferior dog or one of mixed breed" , "Mongrel - coward" .)