Go on to throw marble (6)
I believe the answer is:
ramble
'go on' is the definition.
(rambling is a kind of going on)
'throw marble' is the wordplay.
'throw' is an anagram indicator.
'marble' with letters rearranged gives 'RAMBLE'.
'to' is the link.
(Other definitions for ramble that I've seen before include "Walk or wander" , "Roam about" , "Walk; be discursive" , "Leisurely walk" , "Go as fancy leads" .)