Being colourful, he takes half of us in (3)
I believe the answer is:
hue
'being colourful he' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'takes half of us in' is the wordplay.
'takes' becomes 'he' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'half of' suggests halving the letters.
'in' indicates putting letters inside.
'us' with half the letters taken is 'u'.
'he' enclosing 'u' is 'HUE'.
Can you help me to learn more?
(Other definitions for hue that I've seen before include "Tinge" , "General hubbub - . . . and cry" , "Cast" , "Shade, aspect; Vietnam port" , "appearance" .)