How one sallied in the company of, immediately? (9)
I believe the answer is:
forthwith
'immediately?' is the definition.
(synonyms)
'how one sallied in the company of' is the wordplay.
'how one sallied' becomes 'forth' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in the company of' becomes 'with' (I've seen this in another clue).
'forth'+'with'='FORTHWITH'
Can you help me to learn more?
(Other definitions for forthwith that I've seen before include "Immediately as with froth" , "on the spot" , "Without delay or hesitation" , "without further delay - at which it starts, audibly" .)