Over the moon as family members run away (6)
I believe the answer is:
elated
'over the moon' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
(Other definitions for elated that I've seen before include "Ecstatically happy" , "Greatly delighted and proud" , "Jubilant, overjoyed" , "Hyped up" , "Cock-a-hoop" .)