Welcome back Jolan.
What a joy to see you again.
Thank you for these great clues. All five are high quality (2 is marvellous) and the eureka moments still bring a smile of admiration at your skill.
Here is my stab at them-
1. Mythical sea monster described as a large beast by the academic world (11)- HIPPOCAMPUS?
Large beast – Hippo + campus- academic world gives hippocampus a mythical sea monster?
2. Burn our original locations in action (9) – CAUTERISE?
Case- action with uteri- our original locations- gives cauterise – burn?
3. Curling tongs not found in a gents gathering-room abroad (3,7,4)- THE ROARING GAME?
Subtractive anagram “tongs” out of “a gents gathering-room” gives “the roaring game”- Curling?
4. Long-term con involving retired copper and an early Venus (7)- LUCIFER?
Long term con- lifer +cu (copper) reversed gives Lucifer- morning star and thus early planet Venus?
5. Corresponding with banks may give you some exercise (8,4)- PARALLEL BARS?
Corresponding with – parallel and banks – bars gives something on which you exercise?
Many thanks again.
AB