Retracting of a close to scene in G&S - obscurity round Penzance? (3,3)

'obscurity round penzance?' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'retracting of a close to scene in gs' is the wordplay.
'retracting' says the letters should be written in reverse (I've seen 'retracted' mean this).
'close to' suggests the final letters (the close of something is the end).
'in' indicates putting letters inside.
The final letter of 'scene' is 'e'.
'of'+'a'+'e'='ofae'
'ofae' put into 'gs' is 'gofaes'.
'gofaes' written backwards gives 'SEA-FOG'.

Can you help me to learn more?