Energetic and crucial to be very scathing (13)
I believe the answer is:
hypercritical
'be very scathing' is the definition.
I can't judge whether this defines the answer.
'energetic and crucial' is the wordplay.
'energetic' becomes 'hyper' (hyper can mean hyperactive).
'and' says to put letters next to each other.
'crucial' becomes 'critical' (similar in meaning).
'hyper'+'critical'='HYPERCRITICAL'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for hypercritical that I've seen before include "nit-picking" , "Inclined to judge too severely" , "too disparaging" .)