Slippery Harry Kane wears sporty clothing (6)
I believe the answer is:
sneaky
'slippery' is the definition.
(thesaurus)
'harry kane wears sporty clothing' is the wordplay.
'harry' indicates anagramming the letters (I've seen this in other clues).
'wears' means one lot of letters goes inside another.
'clothing' means to remove the middle letters.
'sporty' with its centre removed is 'sy'.
'kane' is an anagram of 'neak'.
'neak' put within 'sy' is 'SNEAKY'.
(Other definitions for sneaky that I've seen before include "Secretive and sly" , "Treacherous" , "Furtive, underhand" , "Cunning" , "Furtive or given to telling tales" .)