Throttled by lunatic in gruesome killing (5)
I believe the answer is:
icing
'killing' is the definition.
(ice can informally mean to assassinate)
'throttled by lunatic in gruesome' is the wordplay.
'ICING' is hidden in amongst the letters.
However, I'm not sure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for icing that I've seen before include "Attractive addition or bonus, as on cake" , "Cake topper" , "piece of cake?" , "Sugar coating - a danger to aircraft, on roads etc" , "Decorative cake coating" .)