Most in newly rented housing unit to be cast onto the street (9)
I believe the answer is:
trendiest
'most in' is the definition.
(I've seen this before)
'newly rented housing unit to be cast onto the street' is the wordplay.
I cannot really see how this works, but
'unit' could be 't' (T is an example) and 't' is found in the answer.
'be' could be 'end' (ending is a kind of being) and 'end' 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.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for trendiest that I've seen before include "cooler than the rest" , "Most cool!" , "Most popular" .)