Scandinavian pirate’s female leader (6)
I believe the answer is:
viking
'scandinavian pirate's' is the definition.
(I've seen this before)
'female leader' is the wordplay.
'female' becomes 'vi' (short for Violet, a woman's name).
'leader' becomes 'king' (a king is a royal leader).
'vi'+'king'='VIKING'
(Other definitions for viking that I've seen before include "Seafaring Scandinavian" , "One of the early invaders of Ireland" , "Scandinavian raider" , "Norse seafarer" , "Scandinavian warrior" .)