11d. 9 letters. sudden collapse inwards. -m---s---. 17a. 4 letters. dens beginning to like atmosphere. --i-. 25a. 6 letters. peculiar trait. ----t-. 26d. 5 letters. material is dug up. --n-s. 48a. 3 words. 2.1.5.( acquired ) effortlessly. on a -l-t-.