Makes final entreaty for atomiser (7)
I believe the answer is:
sprayer
'atomiser' is the definition.
(I know that atomiser can be written as sprayer)
'makes final entreaty' is the wordplay.
'final' says to take the final letters.
'entreaty' becomes 'prayer' (synonyms).
The last letter of 'makes' is 's'.
's'+'prayer'='SPRAYER'
'for' is the link.
(Other definitions for sprayer that I've seen before include "Dispersing agent - aerosol" , "he'll paint your car" , "Atomiser" , "Device to dispense liquid as a fine mist" , "Device emitting fine droplets" .)