Out of bed and prepared for trouble (5)
I believe the answer is:
upset
'trouble' is the definition.
('upset' can be a synonym of 'trouble')
'out of bed and prepared' is the wordplay.
'out of bed' becomes 'up' ('up' can be a synonym of 'out of bed').
'and' says to put letters next to each other.
'prepared' becomes 'set' (I've seen this before).
'up'+'set'='UPSET'
'for' is the link.
(Other definitions for upset that I've seen before include "Disrupted; knock over" , "Disconcert" , "Knocked over; unhappy" , "Unhappy - unexpected defeat" , "Disturbed or inverted" .)