On vacation, Croatian houses dear in Split (6)
I believe the answer is:
cloven
'split' is the definition.
(I've seen this in another clue)
'on vacation croatian houses dear' is the wordplay.
'on vacation' says to hollow out the word (remove centre letters) (after the inside letters have vacated the word).
'houses' means one lot of letters goes inside another.
'dear' becomes 'love' (synonyms).
'croatian' with its centre taken out is 'cn'.
'cn' going around 'love' is 'CLOVEN'.
'in' acts as a link.
(Other definitions for cloven that I've seen before include "Divided like feet of sheep" , "Like a sheep's hoof" , "(Of hooves) divided" , "Of hoof, divided like oxen" , "Split or divided, as a hoof perhaps" .)