Talia's about gagging, started after nothing to put on toothache (10)

'toothache' is the definition.
(I know that toothache can be written as odontalgia)

'talia's about gagging started after nothing to put on' is the wordplay.
'about' indicates putting letters inside.
'started' suggests taking the first letters.
'after' is a charade indicator (letters next to each other).
'nothing' becomes 'od' (I can't justify this - if you can you should believe this answer much more).
'to put' says to put letters next to each other.
The first letter of 'gagging' is 'g'.
'talia' enclosing 'g' is 'talgia'.
'od'+'on'='odon'
'talgia' after 'odon' is 'ODONTALGIA'.

Can you help me to learn more?