Mad bikers frantic to get off (9)
I believe the answer is:
disembark
'get off' is the definition.
(I've seen this before)
'mad bikers frantic' is the wordplay.
'frantic' indicates an anagram.
'mad'+'bikers'='madbikers'
'madbikers' with letters rearranged gives 'DISEMBARK'.
'to' acts as a link.
(Other definitions for disembark that I've seen before include "Step on dry land" , "Go ashore" , "to set oneself apart from trader, say" , "Get off" .)