Inquisitor 1590

[Ripper]

21 down: National Trust obstructs the path to follow - that's too much! (5) I've got PANTS, but I need it to start with a T.
20 across: Attractive woman nearly stabbed by hard tine that's not been identified (5) H??UR (the letter to change in the definition I think should be M.
27 down: No longer promise to carry (think this changes to Marry) duck that hasn't died (4) A??Y.
31 across Impart (which I think is impaCt) less striking with it medley on the radio (4) ??ES
I could also do with hints on the thematic clues: Metal Bar, Tap & Hawk
Is anyone else singing the ditty, I just can't stop!!!

[scorpiojo]

21 Ta NT o

[ProfessorMaisie]

20a H-HOUR(yes, M)
27d AFFY (yes M)
31a your S is wrong - OLEO (yes C)

[ProfessorMaisie]

Ripper - the metal bar is in the fireplace.
'tap' - think of a 'stop-????' (or do 'it' before you fire a gun?).
'hawk' - a pesterer.

Yes, I can't get rid of the tune either.

[ProfessorMaisie]

...by the way, ticking-off the letters from the phrase in the preamble ('MACHINE GUN...') avoids a possible ambiguity in the last column.

[Ripper]

Thank you Scorpiojo & ProfessorMaisie (for coming to my aid as usual)