Small hatred for element (6)
I believe the answer is:
sodium
'for element' is the definition.
(sodium is a kind of element)
'small hatred' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'hatred' becomes 'odium' (odium is a kind of hatred).
's'+'odium'='SODIUM'
(Other definitions for sodium that I've seen before include "sort of lamp" , "Element discovered by Humphry Davy" , "Chemical in salt" , "It occurs in sea water" , "1 down, symbol Na" .)