Winged Keys
Answer: LOX
As the flavor text hints, each of the clues is for a homophone of a word that fits inside the blanks.
military rank = COLONEL → KERNEL
it contains remains = URN → EARN
"Oh, the Places ____ Go!" = YOU'LL → YULE
stylish = CHIC → SHEIK
hearing-related = AURAL → ORAL
crevasse = FISSURE → FISHER
donut = TORUS → TAURUS
unlawful = ILLICIT → ELICIT
type of rock = GNEISS → NICE
mathematician John = NASH → GNASH
unit of time = HOUR → OUR
supermarket section = AISLE → ISLE
bishop's equal = KNIGHT → NIGHT
rang = TOLLED → TOLD
entirely = WHOLLY → HOLY
it's not GNU = UNIX → EUNUCHS
penny = CENT → SCENT
consumed = ATE → EIGHT
The initial letters fit into the blanks below and spell out KEYS GO IN THESE, but there are only three blanks afterwards. So the answer is not LOCKS, but its homophone LOX.
