European army officer holds permit (3)
I believe the answer is:
let
'permit' is the definition.
('let' can be a synonym of 'permit')
'european army officer holds' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'army officer' becomes 'lt' (I've seen this in other clues).
'holds' indicates putting letters inside.
'e' placed into 'lt' is 'LET'.
(Other definitions for let that I've seen before include "Allow or lease" , "Allowed or rented out" , "Disappoint or fail to support - ... down" , "Umpire's decision" , "inefficient service" .)