Trolls take tumble (4)
I believe the answer is:
roll
'tumble' is the definition.
(tumble can mean to fall or roll)
'trolls take' is the wordplay.
'take' indicates the answer is hidden within the clue (I've seen 'taking' mean this (the answer is carried or taken by the clue)).
'ROLL' is hidden within 'trolls'.
(Other definitions for roll that I've seen before include "Move by turning over" , "on which one is regularly successful" , "Drums sound" , "Turn from side to side" , "Sound of a drum or a list of names" .)