Seaside structure ripe for redevelopment (4)
I believe the answer is:
pier
'seaside structure' is the definition.
(I've seen this before)
'ripe for redevelopment' is the wordplay.
'for redevelopment' indicates an anagram (I've seen this in other clues).
'ripe' anagrammed gives 'PIER'.
(Other definitions for pier that I've seen before include "Landing stage; arch support" , "One jutting into sea" , "Part of airport terminal; breakwater" , "Supporting structure" , "Seaside platform" .)