Pinta's sister ship (4)
I believe the answer is:
nina
'pinta's sister ship' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nina that I've seen before include "Girl" , "Al Hirschfeld's 'hidden' daughter" , "hidden crossword message" , "One of Columbus's ships in 1492; girl's name" , "- - Simone, 1933-2003, singer" .)