Thank breathlessly for a container (4)
I believe the answer is:
tank
'container' is the definition.
(tank is a kind of container)
'thank breathlessly for a' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tank that I've seen before include "A military vehicle or large container" , "Large container for liquid" , "Military machine" , "Possible alternative to barrel" , "Water reservoir" .)