Maybe I'd alarm this officer (7)
I believe the answer is:
admiral
'this officer' is the definition.
(admiral is a kind of officer)
'maybe i'd alarm' is the wordplay.
'maybe' is an anagram indicator.
'id'+'alarm'='idalarm'
'idalarm' anagrammed gives 'ADMIRAL'.
(Other definitions for admiral that I've seen before include "Commander of the fleet or butterfly" , "Naval chief" , "Naval high-up" , "[NELSON] perhaps" , "Highest naval rank" .)