Jabber in chirpy mode, excitedly (10)
I believe the answer is:
Here is my best explanation:
'jabber' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'chirpy mode excitedly' is the subsidiary indication.
'excitedly' indicates an anagram.
'chirpymode' anagrammed gives 'hypodermic'.
'in' is the link.
(Another definition for hypodermic that I've seen is "Type of syringe".)