Creature causes animal-loving children's author to lose the head (5)
I believe the answer is:
otter
'creature' is the definition.
(I know that otter is a type of creature)
'author to lose the head' is the wordplay.
'author' becomes 'potter' (Beatrix Potter 1866-1943).
'to lose the head' means to remove the first letter (I've seen 'losing the head' mean this).
'potter' with its first letter taken away is 'OTTER'.
'causes animal-loving children's' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for otter that I've seen before include "Aquatic member of weasel family" , "Aquatic weasel-like mammal" , "Good swimmer" , "Freshwater brown carnivore" , "River creature" .)