Absolutely right (4,2)
'absolutely right' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bang on that I've seen before include "Absolutely right - sounds noisy" , "Informally and absolutely accurate; it's explosive" , "Talk at length" , "Keep talking tediously" , "Informally, absolutely correct - may be noisy" .)
(Other definitions for spoton that I've seen before include "precisely what is needed" , "Exactly!" , "precise" , "very accurate" .)