A lot of sackcloth offering a thrill in an obvious way? (9)

'a lot' is the definition.
Both the definition and answer are adverbs.
Maybe you can see a link between them that I can't see?

'sackcloth offering a thrill in an obvious way?' is the wordplay.
I cannot really understand how this works, but
'in' is within the answer.
'way?' could be 'l' (abbreviation for left) and 'l' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

'of' acts as a link.

Can you help me to learn more?