Strength of child mentioned (5)
I believe the answer is:
might
'strength' is the definition.
(I know that might is a type of strength)
'child mentioned' is the wordplay.
'child' becomes 'mite' (mite can informally mean a small child).
'mentioned' shows a homophone (sound like).
'mite' is a homophone of 'MIGHT'.
'of' is the link.
(Other definitions for might that I've seen before include "Doubtful" , "May, in the past" , "word expressing possibility" , "- - and main" , "Powerfulness" .)