Appear unexpectedly (5)
'appear unexpectedly' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pop up that I've seen before include "Appear suddenly or unexpectedly" , "three-dimensional picture book" , "which may interrupt computer user" , "Appear (like toast?)" , "book for youngster" .)
'appear unexpectedly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crop up that I've seen before include "Occur unexpectedly - as part of harvest?" , "Appear unexpectedly" , "Occur, arise" , "Occur by chance - like harvest?" , "Occur unexpectedly - like harvest?" .)
(Another definition for popup that I've seen is " What 11 [TOAST] might do".)