Last sign of the Greeks (5)
I believe the answer is:
omega
This could be a double definition.
'last' is the first definition.
(I've seen this in another clue)
'sign of the greeks' is the second definition.
'omega' can be an answer for 'sign' (omega is a kind of sign). I'm not certain of the 'of the greeks' bit.
Can you help me to learn more?
(Other definitions for omega that I've seen before include "Foreign character" , "long letter" , "Last (Gk. letter)" , "Last thing" , "24th Greek letter" .)