A few posers:-
1 Down - "A little bit more time for Rex" (4) M-T- (MITE?)
8 Down - "Star keeping top undone" (4) S-N-
14 Down - "Radiographer's first, not last" (3) R-N (RUN?)
5 Down - "Sooty hearth's earliest fire" (5) S-O-T (obviously
"SHOOT" , but I can't see the first part of the clue! )