but a better clue might have been:
Hereby ruin sonnet? I'ven't a clue, sorry. (7, 5, 6-4)

Shouldn't be hard... Take on muse, upset as before (6)

[Darren] ASSUME.

There appear to be seven currently outstanding:

• An end to land-mines ! Her idea caused split (8) (Blob)
• This clue might be: "500. Follows solid containing volume of mute's heart" (10) (rab)
• Poster confused near narrow road (6) (Chalky)
• Doctor's wrapped up in umbilical cord (MF)
• Small animal run over by learner driver (6) (rab)
• Twisted small mammal eats a chopped nut (6) (Raak)
• Presume the leader is back in place (8) (Blob)

Perhaps some further hints would be in order. Mine contains a misdirection: "Twisted" is the definition part, not a sign of an anagram.

Raak's one has been bothering me for some time now. Some ideas I've had have been TURNED, TURBAN, TRUANT but none of them really seem right. I'm sure when the real answer comes up I'll feel really stupid for missing it. Some explanations of those ideas: I'd realised the "Twisted" misdirection quite early on. Presumably the letters of "nut", chopped (by which I assume anagrammed or split up or both), are in there somewhere, so it comes back to the small mammal. For TURBAN (and yes that's not a great answer for "Twisted") it would be "RAB" (heh) which could be a small form of RABBIT. Very messy, that one. TURNED it would be RED, which I covered above. TRUANT would be RAT, but is TRUANT an answer for "Twisted"? Still, Raak, if you'd be so kind, could you tell me if I'm anywhere near the right lines here?