Greek character twice left some medicine (4)
I believe the answer is:
pill
'medicine' is the definition.
(pill is a kind of medicine)
'greek character twice left some' is the wordplay.
'greek character' becomes 'pi' (letter from the Greek alphabet).
'twice' says to double the letters.
'some' suggests taking the first letters.
The initial letter of 'left' is 'l'.
'l' duplicated is 'll'.
'pi'+'ll'='PILL'
(Other definitions for pill that I've seen before include "Medication" , "Lozenge" , "may be the cure" , "Medical tablet" , "Dreadful person" .)