VIP generous about a historian (6)
I believe the answer is:
gibbon
'a historian' is the definition.
(Edward Gibbon, 1737-1794)
'vip generous about' is the wordplay.
'vip' becomes 'nob' (I've seen this in other clues).
'generous' becomes 'big' (similar in meaning).
'about' shows that the letters should be reversed in order.
'nob'+'big'='nobbig'
'nobbig' reversed gives 'GIBBON'.
(Other definitions for gibbon that I've seen before include "Ape -- author of the 14 15 of the 5 7" , "Asia's native" , "A historian; SE Asian forest creature" , "Animal" , "Long-armed ape" .)