Kinky sex in pool is a blast (9)
I believe the answer is:
explosion
'blast' is the definition.
(thesaurus)
'kinky sex in pool' is the wordplay.
'kinky' indicates anagramming the letters.
'sex'+'in'+'pool'='sexinpool'
'sexinpool' is an anagram of 'EXPLOSION'.
'is a' acts as a link.
(Other definitions for explosion that I've seen before include "Big bang" , "sudden expansion" , "Report" , "Sudden outburst" , "Violent outburst" .)