Semiaquatic snake in Canada? No! (8)
I believe the answer is:
'semiaquatic snake' is the definition.
'anaconda' can be an answer for 'snake' (anaconda is a kind of snake). I am unsure of the 'semiaquatic' bit.
'canada? no' is the wordplay.
'canada? no' anagrams to 'ANACONDA'.
But, I am unsure how the anagram is indicated.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for anaconda that I've seen before include "Large South America snake" , "It can constrict" , "cold-blooded killer" , "Large South American snake" , "Water-boa" .)