Lets out American imprisoned in brawl (6)
I believe the answer is:
tussle
'brawl' is the definition.
(I've seen this before)
'lets out american imprisoned in' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'american' becomes 'us'.
'imprisoned in' indicates putting letters inside.
'lets' with letters rearranged gives 'tsle'.
'tsle' placed around 'us' is 'TUSSLE'.
(Other definitions for tussle that I've seen before include "Brawl" , "'Scuffle, rough-and-tumble (6)'" , "Lets us (anag) - fight" , "Vigorous struggle or scuffle" , "scrap" .)