Very resistant to once more entering lifeless street (4,7)
I believe the answer is:
dead against
'very resistant to' is the definition.
(as in being dead against a proposal)
'once more entering lifeless street' is the wordplay.
'once more' becomes 'again' (synonyms).
'entering' indicates putting letters inside.
'lifeless' becomes 'dead' (similar in meaning).
'street' becomes 'st' (abbreviation).
'dead'+'st'='deadst'
'again' put inside 'deadst' is 'DEAD AGAINST'.
(Other definitions for dead against that I've seen before include "Utterly opposed to (something)" , "Quite hostile to" , "Completely opposed to" .)