Women trimmed flower - the one going to market? What's left, possibly flushed down drain! (5,7)

'left possibly flushed down drain' is the definition.
The definition suggests a singular noun which matches the answer.

'women trimmed flower the one going to market?' is the wordplay.
I cannot quite see how this works, but
'women' could be 'w' (standard abbreviation) and 'w' is located in the answer.
'flower' could be 'r' (abbreviation for river) and 'r' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'one' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
This explanation may well be incorrect...

'what's' acts as a link.

Can you help me to learn more?