Rebuilding pier included in dull plan (9)
I believe the answer is:
blueprint
'plan' is the definition.
(blueprinting is a kind of planning)
'rebuilding pier included in dull' is the wordplay.
'rebuilding' indicates anagramming the letters.
'included in' means one lot of letters goes inside another.
'dull' becomes 'blunt' (similar in meaning).
'pier' is an anagram of 'epri'.
'epri' inserted within 'blunt' is 'BLUEPRINT'.
(Other definitions for blueprint that I've seen before include "Formula" , "Prototype" , "sketch" , "Design or guide for making something" , "Original plan influencing subsequent decisions" .)