Old suite designed for retirement (8)
I believe the answer is:
solitude
'retirement' is the definition.
(thesaurus)
'old suite designed' is the wordplay.
'designed' indicates an anagram (designed with the letters).
'old'+'suite'='oldsuite'
'oldsuite' with letters rearranged gives 'SOLITUDE'.
'for' acts as a link.
(Other definitions for solitude that I've seen before include "Lou diets in isolation" , "Isolation, loneliness" , "Privacy" , "Being by oneself" , "State of being alone without companions" .)