East Sea creature sheds tail in Spring (7)
I believe the answer is:
emanate
'spring' is the definition.
(I've seen this in another clue)
'east sea creature sheds tail' is the wordplay.
'east' becomes 'e' (synonyms).
'sea creature' becomes 'manatee' (I've seen this before).
'sheds tail' means to remove the last letter (I've seen 'shed tail' mean this).
'manatee' with its final letter taken off is 'manate'.
'e'+'manate'='EMANATE'
'in' acts as a link.
(Other definitions for emanate that I've seen before include "Proceed or issue forth" , "Issue forth, from a source" , "spring" , "Issue or spread out from a source" , "Come out (of source)" .)