Look, a new mortgage? (4)
I believe the answer is:
loan
'mortgage?' is the definition.
(I've seen this before)
'look a new' is the wordplay.
'look' becomes 'lo'.
'a new' becomes 'an' (I've seen this in other clues).
'lo'+'an'='LOAN'
(Other definitions for loan that I've seen before include "temporary payment" , "Mortgage" , "It's given but has to be returned" , "Cash advance" , "Something borrowed" .)