Eagerly accept the French whelp (3,2)
I believe the answer is:
Here is my best explanation:
'eagerly accept' is the definition.
(I've seen this before)
'the french whelp' is the subsidiary indication.
'the french' becomes 'la'.
'whelp' becomes 'pup' ('pup' can be a synonym of 'whelp').
(Other definitions for lap up that I've seen before include "Eagerly enjoy", "Drink (water) like a dog", "motor race by some distance?", "Eagerly accept", "Take in willingly (with the tongue?)", "Take in avidly", "of future monarch?", "Scoop", "Accept with obvious pleasure" and "Assimilate with relish".)