London borough cannot remodel houses being erected (6)
I believe the answer is:
merton
'london borough' is the definition.
(I know that Merton is London borough)
'cannot remodel houses being erected' is the wordplay.
'houses' says the answer is hidden in the clue (part of the clue houses the answer).
'being erected' is a reversal indicator (in a down clue, letters go up).
'notrem' can be found hidden inside 'cannot remodel'.
'notrem' back-to-front is 'MERTON'.
(Other definitions for merton that I've seen before include "Comic" , "Oxford college: London borough" .)