They may hold drugs from ace smugglers smuggling a lot of marijuana (8)

'they may hold drugs' is the definition.
The definition suggests an adverb but the answer is not.

'ace smugglers smuggling a lot of marijuana' is the wordplay.
'ace' becomes 'a' (abbreviation).
'smugglers' becomes 'mules' (as in drug mules).
'smuggling' is an insertion indicator (some letters smuggled inside).
'a lot of' means to remove the last letter (a lot of but not all of the word).
'marijuana' becomes 'pot' (slang term for marijuana).
'pot' with its last letter removed is 'po'.
'mules' going around 'po' is 'mpoules'.
'a'+'mpoules'='AMPOULES'

'from' acts as a link.

Can you help me to learn more?