1: Mineral springs start to moderate involuntary muscular contraction (5)
3: Backblock not all there (3)
5: Nightwear and jersey top added in afterthought (3)
7: Gripped by instrument, a longish claw (5)
8: Study a French instrument - it's a puzzle (9)
9: The cow may do this in the local veterinary yard (5)
10: Chatter about some pay-back (3)
12: Taverns quoted cool clique (3)
13: Rambling tales are out of date (5)