A hot-looking French lake recalled as product of volcanism (7)
I believe the answer is:
caldera
'product of volcanism' is the definition.
(a caldera is produced by a volcano)
'a hot-looking french lake recalled' is the wordplay.
'hot-looking' becomes 'red' (red hot).
'french lake' becomes 'lac' ('lake' in French).
'recalled' says the letters should be written backwards.
'a'+'red'+'lac'='aredlac'
'aredlac' reversed gives 'CALDERA'.
'as' acts as a link.
(Other definitions for caldera that I've seen before include "Result of eruption" , "Basin-shaped crater at top of volcano" , "Big hole in rock" , "Large volcanic crater - race lad (anag)" , "Large volcanic crater -- lead car (anag)" .)