Fawn over, with "on” (4)
I believe the answer is:
dote
'fawn over with on' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for dote that I've seen before include "Be overfond" , "Be foolishly fond" , "Be feeble when getting on" , "Group, cluster" , "Love beyond reason" .)