Curious trousers for one firstly in bloomers (7)
I believe the answer is:
nosegay
'bloomers' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'curious trousers for one firstly in' is the wordplay.
'curious' becomes 'nosy' (similar in meaning).
'trousers' is an insertion indicator (trouser can mean to steal or take).
'for one' becomes 'eg' (both can mean 'for example').
'firstly in' becomes 'a' (I am not sure about this - if you are sure you should believe this answer much more).
'eg'+'a'='ega'
'nosy' enclosing 'ega' is 'NOSEGAY'.
Can you help me to learn more?
(Other definitions for nosegay that I've seen before include "Gone, say (anag)" , "Floral offering" , "bunch of pansies?" , "Old-fashioned posy" , "Posy of flowers" .)