Brain is like the weather, foggy!
8a Present-day conclusion? (7) t-n----
4a Take to arms (7) ----a--
7d The last thing a tragedy might do (3,2,8) --d -- -------r
11a Soft Northern dweller may be a shade blue (8) -----i--
17a Risky transaction with a Greek character (4) -e--
21a A first principle in current heaters (7) e---e--
20a He splits a couple of poles made of wood (5) a-h-n (ashen)??