Respectful gesture as second warning may be heard (6)
I believe the answer is:
salaam
'respectful gesture' is the definition.
(respectful gesture in Muslim countries)
'as second warning may be heard' is the wordplay.
I cannot really see how this works, but
'as' could be 'ala' (French 'a la' - 'in the style of') and 'ala' is present in the answer.
'second' could be 's' (common abbreviation) and 's' is present in the answer.
'be' could be 'am' and 'am' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for salaam that I've seen before include "Muslim salutation offering peace" , "Masala (anag) - Arabic greeting" , "Peaceful greeting" , "Eastern greeting" , "Oriental salutation meaning peace" .)