Owls, bizarrely, train tortoise or snail? (9)
I believe the answer is:
slowcoach
'tortoise or snail?' is the definition.
(both are famously slow animals)
'owls bizarrely train' is the wordplay.
'bizarrely' indicates an anagram.
'train' becomes 'coach' (synonyms).
'owls' is an anagram of 'slow'.
'slow'+'coach'='SLOWCOACH'
(Other definitions for slowcoach that I've seen before include "One who takes time to do things" , "Person (or transport?) taking a long time" , "One who lacks liveliness, like old vehicle" , "Snail" , "Laggard" .)