A shelter’s removable locks crop up (6)
I believe the answer is:
wigwam
'a shelter's' is the definition.
'removable locks crop up' is the wordplay.
'removable locks' becomes 'wig' (I've seen this in another clue).
'crop' becomes 'maw' (I've seen this before).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'maw' back-to-front is 'wam'.
'wig'+'wam'='WIGWAM'
(Other definitions for wigwam that I've seen before include "Amerindian home" , "Native American accommodation" , "Tent formerly used by American Indians" , "Tent of skins and poles once used by native Americans" , "Reservation shelter" .)