Watch hooligan's boxing round, all right? (7)
I believe the answer is:
lookout
'watch' is the definition.
(I know that watch can be written as lookout)
'hooligan's boxing round all right?' is the wordplay.
'hooligan' becomes 'lout' (both can mean an aggressive person).
'boxing' means one lot of letters goes inside another ('box' can mean contain, as in to put in a box).
'round' becomes 'o' (round can mean a round object).
'all right?' becomes 'ok' (synonyms).
'o'+'ok'='ook'
'lout' going around 'ook' is 'LOOKOUT'.
(Other definitions for lookout that I've seen before include "A sentry or guard, must be watchful" , "Vantage point" , "Guard on duty" , "Nightwatchman" , "View" .)