I’d pass him irregularly in the centre of Sheffield, say (9)
I believe the answer is:
amidships
'in the centre of sheffield say' is the definition.
(HMS Sheffield was a ship)
'i'd pass him irregularly' is the wordplay.
'irregularly' indicates an anagram.
'id'+'pass'+'him'='idpasshim'
'idpasshim' with letters rearranged gives 'AMIDSHIPS'.
(Other definitions for amidships that I've seen before include "core on board" , "nautical location?" , "Centrally on board" , "moving towards the driest place on board?" , "Toward the centre of the vessel" .)