Disrespectful fans enter river (10)
I believe the answer is:
irreverent
'disrespectful' is the definition.
(similar in meaning)
'fans enter river' is the wordplay.
'fans' indicates anagramming the letters (I've seen 'fan' mean this (letters must be fanned around)).
'enter'+'river'='enterriver'
'enterriver' anagrammed gives 'IRREVERENT'.
(Other definitions for irreverent that I've seen before include "Cheeky" , "Disrespectful" , "Not respectful" , "Impious" .)