They're just what people want (7)
I believe the answer is:
desires
'they're just' is the definition.
The definition suggests an adverb but the answer is not.
'people want' is the wordplay.
I cannot really see how this works, but
'people' could be 'sires' (sire is a kind of person) and 'sires' is found within the answer.
The remaining letters 'de' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'what' is the link.
Can you help me to learn more?
(Other definitions for desires that I've seen before include "needs" , "Wants (7)." , "Covets and yearns for" , "Hopes" , "Wishes" .)