Related Clues:
- Aseptic or infertile
- Incapable of reproducing
- When the cigarette's dead, that seems to be what's happened to make one mullish
- Make the rest lie so that it can't go to the bad (7)
- Like most mules
- Showing dogged determination
- Never giving up Bob's turn at sea
- Butt originating with the head of a pig?
- Unproductive poster I left hidden
- Maybe Lister had a point making things so
- No issue is sure when this queen is in step
- Mulish objections raised and natural to follow
- Lacking potentialilty of sire, let off
- A few steps required to keep emergency room bug-free
- Refractory