Kid's utterance, eating chap's plum (7)
I believe the answer is:
magenta
'plum' is the definition.
(thesaurus)
'kid's utterance eating chap's' is the wordplay.
'kid's utterance' becomes 'maa' (I can't justify this - if you can you should give a lot more credence to this answer).
'eating' indicates putting letters inside.
'chap' becomes 'gent' (both can mean a man).
'maa' going around 'gent' is 'MAGENTA'.
Can you help me to learn more?
(Other definitions for magenta that I've seen before include "French victory" , "Colour named after a bloody 1859 battle in Italy" , "Colourful" , "Purplish-red - battle" , "Light purplish-red" .)