A mother with energy - wonderful (7)
I believe the answer is:
amazing
'wonderful' is the definition.
(I've seen this before)
'a mother with energy' is the wordplay.
'mother' becomes 'ma' (Ma is another word for mother or mum).
'with' says to put letters next to each other.
'energy' becomes 'zing' (I've seen this before).
'a'+'ma'+'zing'='AMAZING'
(Other definitions for amazing that I've seen before include "Sensational" , "Very impressive" , "description of Grace?" , "Gobsmackingly great!" , "Awesome, astounding" .)