Quick tongue, yet serpentine, in two parts? (7-5)
I believe the answer is:
lickety-split
'quick' is the definition.
(thesaurus)
'tongue yet serpentine in two parts?' is the wordplay.
'tongue' becomes 'lick'.
'serpentine' is an anagram indicator (a twisting or serpentine form of the letters).
'in two parts?' becomes 'split' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'yet' is an anagram of 'ety'.
'lick'+'ety'+'split'='LICKETY-SPLIT'
Can you help me to learn more?
(Other definitions for lickety-split that I've seen before include "(In the US) at once" , "Without delay" , "As fast as possible" , "Speedily" .)