I believe the answer is:
'impudence' is the definition.
(I know that impudence can be written as gall)
This is the entire clue.
(Other definitions for gall that I've seen before include "Impudence, cheek" , "Audacity" , "Irritate - presumption" , "Spleen or brass neck" , "Bitterness of feeling or bodily bladder" .)