Intelligible commanding officer - he gets payment (8)
I believe the answer is:
coherent
'intelligible' is the definition.
(I've seen this before)
'commanding officer he gets payment' is the wordplay.
'commanding officer' becomes 'co'.
'gets' says to put letters next to each other.
'payment' becomes 'rent' (rent is a kind of payment).
'co'+'he'+'rent'='COHERENT'
(Other definitions for coherent that I've seen before include "Rational" , "Holding together as a whole" , "Sticking together" , "Not rambling in speech or reasoning" , "Able to speak logically" .)