Taking part in Paris-Dakar is known to be a gamble (4)
I believe the answer is:
risk
'a gamble' is the definition.
(thesaurus)
'taking part in paris-dakar is known' is the wordplay.
'taking part in' indicates a hidden word.
'RISK' can be found hidden inside 'paris dakar is known'.
'to be' is the link.
(Other definitions for risk that I've seen before include "Endanger, jeopardise" , "Assessment of potential dangers -- any silk saris (anag)" , "dangerous thing" , "Jeopardy" , "Danger or hazard" .)