6d Gap in a piece of wood (8)
" K N - - - M - E "
11a Arrangement in poetry or music (3,4)
" A - - - O - M "
20a Most impervious to light (8)
" O - A - U - - T "
25a Conspicuous and outrrageously bad (9)
" E - - E - I - U - "
27a Desperate enterprise of last resort (7,4)
" F - R - - R - H - P E "