An ancient king was given it as a custom (4)

I believe the answer is:

ahab

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

'an ancient king' is the definition.
'ahab' can be an answer for 'king' (I've seen this before). I'm not certain of the 'an ancient' bit.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for ahab that I've seen before include "Jezebel's husband - Moby Dick's hunter" , "Captain in search of Moby Dick" , "Jezebel's husband or captain in 'Moby Dick'" , "sea captain" , "Captain hunting the whale Moby-Dick" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app