Judge rebuilt pier after hesitation (6)
I believe the answer is:
umpire
'judge' is the definition.
(I know this)
'rebuilt pier after hesitation' is the wordplay.
'rebuilt' is an anagram indicator.
'after' says to put letters next to each other.
'hesitation' becomes 'um' (um is said in hesitation).
'pier' is an anagram of 'pire'.
'pire' put after 'um' is 'UMPIRE'.
(Other definitions for umpire that I've seen before include "Arbiter of cricket match" , "Arbitrator (in certain sports)" , "Football official" , "Official at a cricket match" , "Sports arbiter" .)