Hunting dog terribly loud, Ken holding lead in hall (8)
I believe the answer is:
elkhound
'hunting dog' is the definition.
(elkhound is a kind of hunting dog)
'terribly loud ken holding lead in hall' is the wordplay.
'terribly' indicates an anagram.
'holding' indicates putting letters inside.
'lead in' suggests taking the first letters.
The initial letter of 'hall' is 'h'.
'loud'+'ken'='loudken'
'loudken' anagrammed gives 'elkound'.
'elkound' going around 'h' is 'ELKHOUND'.
(Other definitions for elkhound that I've seen before include "one of our best friends?" , "Norwegian dog" .)