Flexible resort hotels to entertain one with massage on vacation (9)
I believe the answer is:
lithesome
'flexible' is the definition.
(I've seen this before)
'resort hotels to entertain one with massage on vacation' is the wordplay.
'resort' indicates an anagram.
'to entertain' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'with' means one lot of letters go next to another.
'on vacation' suggests removing the centre.
'massage' with its centre taken out is 'me'.
'hotels' is an anagram of 'ltheso'.
'ltheso' going around 'i' is 'litheso'.
'litheso'+'me'='LITHESOME'
(Other definitions for lithesome that I've seen before include "flexibility" , "Graceful" , "Willowy" , "slim and supple" , "Flexible" .)