Atoll and skimpy swimsuit (6)
I believe the answer is:
bikini
'atoll and skimpy swimsuit' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bikini that I've seen before include "Two piece swimsuit" , "Beach clothing" , "Two-piece cozzie" , "Bathing suit for the atoll?" , "Skimpy beachwear" .)