Dan Quayle's successor (2,4)
I believe the answer is:
al gore
'dan quayle's successor' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for al gore that I've seen before include "American Vice-President to Bill Clinton" , "1990s US vice-president" , "Bill Clinton's vice president" , "Bill Clinton's vice-president" , "George Bush defeated him for the presidency" .)