False identity (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
alias
'false identity' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for alias that I've seen before include "False or assumed name" , "it may be assumed" , "Otherwise known as" , "Cabbage salad" , "Otherwise - an assumed name" .)