Polished like a puppy (6)
I believe the answer is:
snappy
'polished' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I don't see?
'like a puppy' is the wordplay.
I cannot quite see how this works, but
'like' could be 'y' (similar in meaning) and 'y' is located in the answer.
'a' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for snappy that I've seen before include "without hesitation" , "Irritably abrupt" , "Irritable - smart" , "as a croc?" , "Short-tempered" .)