Cable conveying officer's agreement (7)
I believe the answer is:
concord
'agreement' is the definition.
(I know that agreement can be written as concord)
'cable conveying officer's' is the wordplay.
'cable' becomes 'cord'.
'conveying' is an insertion indicator.
'officer' becomes 'NCO' (abbreviation for non-commissioned officer).
'cord' placed around 'nco' is 'CONCORD'.
(Other definitions for concord that I've seen before include "Harmony; treaty" , "Amity" , "Harmonious state of things" , "Agreement, harmony" .)