。
I wish the fog would clear soon.
Literal
Fog [subject-が] soon clear [favor-くれれば] good [explanatory-んだが].
晴れてくれる uses ~てくれる to ask for the favor (even from an inanimate entity — 'I wish the fog would do me the favor of clearing'). ~ばいいんだが = 'if X, that would be good, but...' — wistful/hopeful. A layered expression of hope.