The senior officer, I see, has a complaint (5)
I believe the answer is:
colic
'a complaint' is the definition.
(medical complaint)
'the senior officer i see' is the wordplay.
'the senior officer' becomes 'col' (abbreviation for colonel).
'see' becomes 'c' (the word for the letter, according to Chambers).
'col'+'i'+'c'='COLIC'
'has' acts as a link.
(Other definitions for colic that I've seen before include "Acute abdominal pain" , "Abdominal pain spasms" , "one for babies" , "Gripe" , "Abdominal pain, especially in infants" .)