Develop dilapidated US port (6)
I believe the answer is:
sprout
'develop' is the definition.
(sprouting is a kind of developing)
'dilapidated us port' is the wordplay.
'dilapidated' indicates an anagram.
'us'+'port'='usport'
'usport' anagrammed gives 'SPROUT'.
(Other definitions for sprout that I've seen before include "Small cabbage from Brussels?" , "Spring up like vegetable from Brussels" , "Bud; a type of cabbage" , "Put out shoots for a brassica" , "Produce shoots; vegetable" .)