Sign from galleon (3)
I believe the answer is:
'sign' is the definition.
'from galleon' is the wordplay.
'from' indicates the answer is hidden within the clue.
'LEO' is hidden within 'galleon'.
(Other definitions for leo that I've seen before include "certain stars" , "one of several popes" , "Cancer, ___, Virgo" , "Man" , "Horoscope sign" .)