Stronghold originally contained elaborate detail (7)
I believe the answer is:
citadel
'stronghold' is the definition.
(I know that citadel is a type of stronghold)
'originally contained elaborate detail' is the wordplay.
'originally' indicates taking the first letters.
'elaborate' is an anagram indicator (I've seen this in other clues).
The first letter of 'contained' is 'c'.
'detail' is an anagram of 'itadel'.
'c'+'itadel'='CITADEL'
(Other definitions for citadel that I've seen before include "Stronghold (of the Salvation Army?)" , "secure place" , "Kremlin" , "Fort, fastness" , "Fortress overlooking a city" .)