Signal to stop bombardment (4)
I believe the answer is:
hail
This clue could be a double definition.
'signal' is the first definition.
(thesaurus)
'stop bombardment' is the second definition.
'hail' can be an answer for 'bombardment' (thesaurus). I'm not sure about the 'stop' bit.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for hail that I've seen before include "Greet enthusiastically" , "Greeting - falling stones" , "Greet - bad weather" , "Precipitating ice pellets" , "Shower of ice pellets" .)