Prehistoric item originally accommodated by girl in charge (7)
I believe the answer is:
liassic
'prehistoric' is the definition.
Both the definition and answer are adjectives.
Perhaps you can see an association between them that I don't see?
'item originally accommodated by girl in charge' is the wordplay.
'originally' says to take the initial letters.
'accommodated by' means one lot of letters goes inside another.
'girl' becomes 'lass' (lass can informally mean a girl).
'in charge' becomes 'ic' (abbreviation for 'in charge').
The first letter of 'item' is 'i'.
'i' inserted within 'lass' is 'liass'.
'liass'+'ic'='LIASSIC'
Can you help me to learn more?
(Other definitions for liassic that I've seen before include "from around 200 million years ago" , "Relating to part of the Jurassic period" , "Relating to early Jurassic" .)