Strange jet ski barely starts (5)
I believe the answer is:
kinky
'strange' is the definition.
(thesaurus)
'jet ski barely starts' is the wordplay.
'jet' becomes 'inky' (I've seen this in another clue).
'barely' says to take the centre (the word is bare of its external letters).
'starts' is a charade indicator (letters next to each other).
The middle letter of 'ski' is 'k'.
'inky' after 'k' is 'KINKY'.
(Other definitions for kinky that I've seen before include "Twisted" , "Given to deviant sexual practices" , "Deviant, eccentric" , "Sexually unusual" , "Irritatingly self-satisfied" .)