Vape stuff on front of desk in small quantity (8)

'small quantity' is the definition.
'decigram' can be an answer for 'quantity' (decigram is a kind of quantity). I'm not sure about the 'small' bit.

'vape stuff on front of desk' is the wordplay.
'vape' becomes 'ecig' (I can't explain this - if you can you should believe this answer much more).
'stuff' becomes 'ram' (ram can mean to stuff or push).
'on' says to put letters next to each other.
'front of' says to take the initial letters (the letter at the front of the word).
The first letter of 'desk' is 'd'.
'ecig'+'ram'='ecigram'
'ecigram' after 'd' is 'DECIGRAM'.

'in' is the link.

Can you help me to learn more?