Rule out getting married to animal (5)
I believe the answer is:
lemur
'to animal' is the definition.
(lemur is a kind of animal)
'rule out getting married' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'getting' is an insertion indicator.
'married' becomes 'm'.
'rule' anagrammed gives 'leur'.
'leur' placed around 'm' is 'LEMUR'.
(Other definitions for lemur that I've seen before include "Madagascan monkey" , "Arboreal animal" , "Animal with foxy face and long furry tail" , "Large-eyed animal with foxy face and furry tail" , "Monkey-like animal of Madagascar" .)