Believable story involving a new dog (7)
I believe the answer is:
spaniel
'dog' is the definition.
(spaniel is a kind of dog)
'believable story involving a new' is the wordplay.
'believable story' becomes 'spiel' (I can't justify this - if you can you should believe this answer much more).
'involving' indicates putting letters inside.
'a new' becomes 'an' (I've seen this in other clues).
'spiel' placed around 'an' is 'SPANIEL'.
Can you help me to learn more?
(Other definitions for spaniel that I've seen before include "Droopy-ear dog" , "Long-eared dog" , "See 1 Across" , "Dog with long silky coat" , "Alpines (anag)" .)