Thanks to the building of an ark, we have the otter (5)
I believe the answer is:
tarka
'otter' is the definition.
(I've seen this before)
'thanks to the building of an ark' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'to the building of' is an anagram indicator (I've seen 'building' mean this).
'ark' with letters rearranged gives 'rka'.
'ta'+'rka'='TARKA'
'we have the' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for tarka that I've seen before include "Fictional otter" , "Swimmer in story" , "Devon swimmer" , "- - the Otter by H Williamson" , "Henry Williamson's otter" .)