Werll; done, Ixion! Thanks all. Herwith my own analysis, just for completion.
1. complex anag (unrestrained) of ‘charioteers’ – ‘it’ = RACEHORSE (can take part in a chase = steeplechase)
2. (cryptic) car case = CARCASE = body
3. (double and cryptic) SHORT ORDER = food that can be prepared quickly (Chambers Dict). Also had to include the apostrophe to agree with Chambers def of ‘shun = attention! – a military order. Attention! is the order and, of course, ‘Shun is the SHORT ORDER
4. writer = FELT TIP. experienced = felt; clue = tip
5. anag(building) of ‘towers’ in mark = old German capital, yields MASTERWORK = one’s greatest achievement (Chambers).