Combine in emergencies (5)
I believe the answer is:
merge
'combine' is the definition.
(I know that combine can be written as merge)
'in emergencies' is the wordplay.
'in' indicates a hidden word.
'MERGE' is hidden in the letters of 'emergencies'.
(Other definitions for merge that I've seen before include "Become combined" , "Combine, blend" , "Combine, coalesce" , "Come together as one" , "Mix" .)