Rented one incredible resort to relax (3,2,3,4,3)
I believe the answer is:
let it all hang out
'relax' is the definition.
(I've seen this before)
'rented one incredible resort' is the wordplay.
'rented' becomes 'let' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'incredible' becomes 'tall' (as in a tall tale).
'resort' becomes 'hangout' ('hangout' can be a synonym of 'resort'**).
'let'+'i'+'tall'+'hangout'='LET IT ALL HANG OUT'
'to' acts as a link.
(Other definitions for let it all hang out that I've seen before include "finished the washing, perhaps" , "Put everything on the washing line" , "Be completely uninhibited" , "hold nothing back?" , "Relax totally" .)