Advance across rolling sand in promontory (5,3)

I believe the answer is:

land's end

'promontory' is the definition.
(I've seen this before)

'advance across rolling sand' is the wordplay.
'advance' becomes 'lend' (I've seen this before).
'across' means one lot of letters goes inside another.
'rolling' indicates anagramming the letters.
'sand' anagrammed gives 'ands'.
'lend' placed around 'ands' is 'LANDS END'.

'in' acts as a link.

I've seen this clue in The Telegraph.

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