Allied prisoners held there found army officer quite scatterbrained, in short (7)
I believe the answer is:
colditz
'allied prisoners held there found army' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'officer quite scatterbrained in short' is the wordplay.
'officer quite' becomes 'col' (abbreviation for colonel, an army officer. I am not sure about the 'quite' bit.).
'scatterbrained' becomes 'ditzy' (I've seen this in another clue).
'in short' means to remove the last letter.
'ditzy' with its last letter removed is 'ditz'.
'col'+'ditz'='COLDITZ'
Can you help me to learn more?
(Other definitions for colditz that I've seen before include "German wartime prison" , "Castle used as a POW camp for Allied officers, 1940-45" , "WWtwo high-security POW camp" , "Oflag IV-C" , "Castle holding POWs" .)