Animal showing excessive hesitation (5)
I believe the answer is:
Here is my best explanation:
'animal' is the definition.
(I've seen this before)
'excessive hesitation' is the subsidiary indication.
'excessive' becomes 'ott' (short for 'over the top' - informal British).
'hesitation' becomes 'er'.
'showing' is the link.
(Other definitions for otter that I've seen before include "A river mammal", "Web-footed mammal", "Fish-eating mammal", "Something furry", "Freshwater brown carnivore", "Playful aquatic animal of 'Tarka' fame", "carnivore is concerned", "Fur possibly", "Semi-aquatic mammal" and "fish-eater displayed".)