Ripe design for wharf (4)
I believe the answer is:
pier
'wharf' is the definition.
(thesaurus)
'ripe design' is the wordplay.
'design' indicates anagramming the letters.
'ripe' is an anagram of 'PIER'.
'for' is the link.
(Other definitions for pier that I've seen before include "Support for two adjacent bridge spans" , "Seaside platform" , "Break-water or landing stage" , "Seaside resort feature" , "Platform out to sea" .)