American writer's sense of smell repulsed, taking in sea at Calais (7)
I believe the answer is:
emerson
'american writer's' is the definition.
(I've seen this before)
'sense of smell repulsed taking in sea at calais' is the wordplay.
'sense of smell' becomes 'nose' (nose is a kind of sense of smell).
'repulsed' says the letters should be written backwards.
'taking in' means one lot of letters goes inside another.
'sea at calais' becomes 'mer' (I can't explain this - if you can you should give a lot more credence to this answer).
'nose' in reverse letter order is 'eson'.
'eson' going around 'mer' is 'EMERSON'.
Can you help me to learn more?
(Other definitions for emerson that I've seen before include "American poet and philosopher, d. 1882" , "Ralph Waldo . . ., 19th century American philosopher and poet" , "Ralph Waldo --, US author" , "American author, 1803-82" , "Ralph Waldo ......., 19th century American transcendentalist" .)