Legendary caveman having a fling (6)

I believe the answer is:

fingal

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

'legendary caveman' is the definition.
'fingal' can be an answer for 'caveman' (I've seen this before). I'm not certain of the 'legendary' bit.

'a fling' is the wordplay.
'a fling' anagrams to 'FINGAL'.
But, I'm not clear how this is indicated.

'having' is the link.

Can you help me to learn more?

(Other definitions for fingal that I've seen before include "Caveman" , "His cave is on Staffa" , "Epic Scot" .)

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.