Alright for a Greek character to have animal (5)
I believe the answer is:
Here is my best explanation:
'animal' is the definition.
'alright for a greek character' is the wordplay.
'alright' becomes 'ok' ('OK' can be a synonym of 'alright').
'for' means one lot of letters go next to another.
'greek character' becomes 'pi' (letter from the Greek alphabet).
'to have' is the link.
(Other definitions for okapi that I've seen before include "Type of giraffe", "Beast related to giraffe", "creature", "Giraffe relative", "Animal related to giraffe", "african", "Giraffe family mammal", "Animal of central Africa", "African leaves fancier" and "Browser".)