Island involved in risky experiment (4)
I believe the answer is:
skye
'island' is the definition.
(I've seen this before)
'involved in risky experiment' is the wordplay.
'involved in' indicates the answer is hidden within the clue.
'SKYE' is hidden within 'risky experiment'.
(Other definitions for skye that I've seen before include "Island - keys (anag)" , "Home of the Cuillin mountains" , "part of Scotland" , "Portree island" , "Hebridean island close to mainland" .)