Radical junior in charge too high to catch? (10)
I believe the answer is:
ultrasonic
'too high to catch?' is the definition.
I can't tell whether this defines the answer.
'radical junior in charge' is the wordplay.
'radical' becomes 'ultra' (synonyms).
'junior' becomes 'son'.
'in charge' becomes 'ic' (abbreviation for 'in charge').
'ultra'+'son'+'ic'='ULTRASONIC'
Can you help me to learn more?
(Other definitions for ultrasonic that I've seen before include "Higher than can be heard" , "Involving sound waves beyond human hearing" , "Above the limit of human hearing" , "Of high frequency" .)