Helping sailor, say, around racing event? Cool! (8)
I believe the answer is:
abetting
'helping' is the definition.
(to abet is to aid or assist)
'sailor say around racing event? cool' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'say' becomes 'eg' (both can mean for example).
'around' means one lot of letters goes inside another.
'racing event?' becomes 'TT' (Isle of Man Tourist Trophy races).
'cool' becomes 'in' ('in' can mean fashionable or cool).
'tt'+'in'='ttin'
'eg' enclosing 'ttin' is 'etting'.
'ab'+'etting'='ABETTING'
(Other definitions for abetting that I've seen before include "Encouraging, assisting" , "Assisting, in wrongdoing usually" , "Helping (a criminal)" , "Aiding and helping" , "Backing" .)