SIS

Little sibling (3)

Solution has appeared in 2 crosswords (1 across and 1 down):

• Quick crossword No 16,390 — 2022-11-17 00:00:33
  21A: Bro's sibling (3)
• Quick crossword No 15,249 — 2019-03-23 00:00:08
  23D: Little sibling (3)