Child power makes itself heard (4)
I believe the answer is:
mite
'child' is the definition.
(mite can informally mean a small child)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for mite that I've seen before include "The Biblical widow's offering" , "Little chap" , "Minute creature" , "Minute arachnid" , "The widow's contribution, just in time" .)