Heads of state wept on being believed (9)
I believe the answer is:
swallowed
'believed' is the definition.
(swallowing is a kind of believing)
'heads of state wept on being' is the wordplay.
'heads of' suggests taking the first letters.
'on being' becomes 'allowed' (I can't justify this - if you can you should believe this answer much more).
The initial letters of 'state wept' is 'sw'.
'sw'+'allowed'='SWALLOWED'
Can you help me to learn more?
(Other definitions for swallowed that I've seen before include "Gulped" , "Meekly accepted" , "drunk maybe" , "believed" , "Ingested" .)