Holiday rentals for threesome (8)
I believe the answer is:
triplets
'holiday rentals for threesome' is the definition.
I can't judge whether this defines the answer.
'rentals for threesome' is the wordplay.
'rentals' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'for' says to put letters next to each other (I've seen this in other clues).
'threesome' becomes 'triplet' (synonyms).
's' after 'triplet' is 'TRIPLETS'.
Can you help me to learn more?
(Other definitions for triplets that I've seen before include "three children to come together" , "Splitter (anag)" , "Three born at the same time" .)