Find curtain rail on the floor (5,4)
I believe the answer is:
track down
'find curtain' is the definition.
'track down' can be an answer for 'find' (I've seen this before). I am unsure of the 'curtain' bit.
'rail on the floor' is the wordplay.
'rail' becomes 'track' (synonyms).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the floor' becomes 'down' (both can mean to knock to the ground).
'track'+'down'='TRACK DOWN'
Can you help me to learn more?
(Other definitions for track down that I've seen before include "Find (something) after long search" , "Finally discover" , "path from the summit" , "railway's state after landslide?" , "what railway constructor needs to get" .)