Do people need to be in it? (4)
I believe the answer is:
want
'do people need' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'be in it?' is the wordplay.
'be in' becomes 'wan' (I can't justify this - if you can you should believe this answer much more).
'wan'+'t'='WANT'
'to' is the link.
Can you help me to learn more?
(Other definitions for want that I've seen before include "Desire - deficiency" , "Need or desire" , "Wish" , "Lack, desire" , "Crave" .)