Half of medicals returned the same (4)
I believe the answer is:
idem
'same' is the definition.
(I've seen this in another clue)
'half of medicals returned' is the wordplay.
'half of' means to take half the letters.
'returned' shows that the letters should be reversed in order.
'medicals' cut in half is 'medi'.
'medi' in reverse letter order is 'IDEM'.
'the' acts as a link.
(Other definitions for idem that I've seen before include "Ditto for a dime" , "The same as just mentioned, to old Romans" , "The same (as just mentioned) (Latin)" , "[DOUBLE]" , "The same for an odd dime" .)