Dam -- peculiar, no end (4)
I believe the answer is:
weir
'dam' is the definition.
(a weir is a type of dam)
'peculiar no end' is the wordplay.
'peculiar' becomes 'weird' (I've seen this in another clue).
'no end' means to remove the last letter.
'weird' with its last letter taken off is 'WEIR'.
(Other definitions for weir that I've seen before include "River flow regulator" , "Structure for raising water level in river" , "Low dam across a river" , "hazard during 14" , "Low dam built across a stream" .)