Sprinter jinks round dog in dangerous races (3,8)

'dangerous races' is the definition.
(dangerous racing currents of water)

'sprinter jinks round dog' is the wordplay.
'jinks' indicates anagramming the letters (jink can mean to change direction or move).
'round' indicates putting letters inside.
'dog' becomes 'cur' (cur is a kind of dog).
'sprinter' with letters rearranged gives 'riprents'.
'riprents' enclosing 'cur' is 'RIP CURRENTS'.

'in' acts as a link.