Had animosity towards and detested, initially (5)

I believe the answer is:

hated

I'm a little stuck... Click here to teach me more about this clue!

'detested initially' is the definition.
'hated' can be an answer for 'detested' ('hate' can be a synonym of 'detest'). I'm not certain of the 'initially' bit.

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for hated that I've seen before include "Seriously disliked" , "Despised" , "Heartily disliked" , "was unable to stand" , "Abominated" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.