Forgo a ticket to the top (4,2)
I believe the answer is:
pass up
'forgo' is the definition.
(I've seen this in another clue)
'a ticket to the top' is the wordplay.
'a ticket' becomes 'pass' (pass is a kind of ticket).
'to the top' becomes 'up' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pass'+'up'='PASS UP'
Can you help me to learn more?
(Other definitions for pass up that I've seen before include "Have nothing to do with" , "Refuse - reject" , "Ignore" , "forego" , "Miss" .)