Charge for a sign (3)
I believe the answer is:
ram
I believe this clue is a double definition.
'charge' is the first definition.
(I've seen this in other clues)
'sign' is the second definition.
(Aries the Ram, sign of the zodiac)
'for a' is the link.
(Other definitions for ram that I've seen before include "Object to batter with" , "Prepare to raid" , "Computer memory of a sheep?" , "Pound" , "The constellation Aries" .)