Army officer in centre, by the sound of it (7)
I believe the answer is:
colonel
'army officer' is the definition.
(I've seen this before)
'centre by the sound of it' is the wordplay.
'centre' becomes 'kernel' (I've seen this before).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'kernel' is a homophone of 'COLONEL'.
'in' is the link.
(Other definitions for colonel that I've seen before include "Rank (below brigadier)" , "Commissioned officer" , "Army rank" , "Army officer ranking below a brigadier" , "soldier" .)