Crave unlimited wealth? Get away! (6)
I believe the answer is:
begone
'get away' is the definition.
(command to be gone)
'crave unlimited wealth?' is the wordplay.
'crave' becomes 'beg'.
'unlimited' says to take the centre (remove the limits/outer letters).
'wealth?' becomes 'money' (money is a kind of wealth).
The centre of 'money' is 'one'.
'beg'+'one'='BEGONE'
(Other definitions for begone that I've seen before include "Archaic injunction to go away" , "Archaic word of dismissal" , "shove off" , "Take a hike" , "Archaic command to buzz off" .)