Large demons violated megalithic tombs (7)

I believe the answer is:

dolmens

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

'tombs' is the definition.
(I know this)

'large demons violated' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'violated' is an anagram indicator (letters violated or damaged).
'l'+'demons'='ldemons'
'ldemons' anagrammed gives 'DOLMENS'.

'megalithic' is the link.
This may not be correct. It may belong to another bit of the clue.

Can you help me to learn more?

(Another definition for dolmens that I've seen is " gravestones".)

I've seen this clue in The Irish Times.

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