Also called a torn sail (5)
I believe the answer is:
alias
'also called' is the definition.
(I've seen this in another clue)
'a torn sail' is the wordplay.
'torn' indicates an anagram.
'sail' anagrammed gives 'lias'.
'a'+'lias'='ALIAS'
(Other definitions for alias that I've seen before include "Otherwise called" , "Otherwise known as" , "Cabbage salad" , "Alternative identity" , "Otherwise - an assumed name" .)