Relating to or resembling an ape (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
simian
(Other definitions for simian that I've seen before include "Ape; apelike" , "Monkey-like" , "Monkey, say," , "To do with or looking like a monkey" , "Resembling an ape or monkey" .)