They are charged for half portions (4)
I believe the answer is:
ions
'they are charged' is the definition.
The definition suggests an adverb but the answer is not.
'half portions' is the wordplay.
'half' indicates taking half.
'portions' cut in half is 'IONS'.
'for' is the link.
Can you help me to learn more?
(Other definitions for ions that I've seen before include "Electrically-charged particles" , "items with a charge" , "Electrically charged particles" , "Charged atom or molecule" , "N in radio comms." .)