Got up to fix siren (5)
I believe the answer is:
risen
'got up' is the definition.
('rise' can be a synonym of 'get up')
'fix siren' is the wordplay.
'fix' is an anagram indicator.
'siren' with letters rearranged gives 'RISEN'.
'to' is the link.
(Other definitions for risen that I've seen before include "Out of bed" , "Ascended - revolted" , "mounted a rebellion" , "Proved" , "Above the horizon" .)