After redevelopment, sea site most comfortable (7)
I believe the answer is:
easiest
'most comfortable' is the definition.
('easy' can be similar in meaning to 'comfortable')
'after redevelopment sea site' is the wordplay.
'after redevelopment' indicates anagramming the letters.
'sea'+'site'='seasite'
'seasite' is an anagram of 'EASIEST'.
(Other definitions for easiest that I've seen before include "most amenable" , "Requiring the least amount of effort" , "Most effortless" , "Least hard" , "Most convenient" .)