Bow milliner, perhaps, put on line second (6)
I believe the answer is:
latter
'second' is the definition.
'bow milliner perhaps put on line' is the wordplay.
I cannot really understand how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
'line' could be 'l' and 'l' is located in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for latter that I've seen before include "Last-mentioned" , "Second of two choices" , "That follows" , "The one just mentioned" , "Second mentioned of two" .)