Lose head in fight on the town (3)
I believe the answer is:
out
'on the town' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for out that I've seen before include "what batsman doesn't want to be" , "SECOND PART OF 16" , "No longer in prison" , "not acceptable" , "Escaped" .)