Hundreds on planet in want (6)
I believe the answer is:
dearth
'want' is the definition.
(dearth is a kind of want)
'hundreds on planet' is the wordplay.
'hundreds' becomes 'd' (I've seen this in other clues**).
'on' is a charade indicator (letters next to each other).
'planet' becomes 'earth' (Earth is an example).
'd'+'earth'='DEARTH'
'in' is the link.
(Other definitions for dearth that I've seen before include "Red hat for scarcity" , "Scarcity of thread" , "Hatred (anag) -- shortage" , "From shortage of food" , "Shortage, lack" .)