By the lake, one will tie up (4)
I believe the answer is:
lace
'tie up' is the definition.
(I've seen this in another clue)
'by the lake one' is the wordplay.
'by' says to put letters next to each other.
'the lake' becomes 'l' (geographical abbreviation).
'one' becomes 'ace' (ace has a value of one in some card games).
'l' next to 'ace' is 'LACE'.
'will' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for lace that I've seen before include "Tear" , "Famous play ''Arsenic and Old . . . .''" , "A fabric; add alcohol to" , "Shoe tie" , "Delicate fabric woven in an open web" .)