Sorry! I couldn't find any that start with robe, but did find one that ends with it:
-wardrobe
Sorry!
Fallback is a compound word. Falloff and fallout are compound words.
The answer is become.
teardrop gumdrop raindrop dewdrop backdrop
Doable
zebralicious
One such word is whenever.
airtimeanytimebedtimedowntimelunchtimemealtimeovertimeplaytimesometimespringtimesummertimetimebasetimeouttimesharewintertime
Robe
backbonebackgroundballparkbaseballbaseboardbasketballbathhousebathtubbathwaterbirdhousebirthdaybirthmarkbirthrightblackbirdblackboardblackmailbloodbathbookmarkbookshelfbluebellbluebirdblueprintboyhoodbrainwavebreadwinnerbreakwaterbrownstonebutterball
Snail
roommate
"Lukewarm."