A charge on collection (5)

I believe the answer is:

onset

'a charge' is the definition.
(thesaurus)

'on collection' is the wordplay.
'collection' becomes 'set' (set is a kind of collection).
'on'+'set'='ONSET'

(Other definitions for onset that I've seen before include "Start - notes (anag)" , "Beginning or early stages" , "Appearance of" , "Outbreak" , "Beginning; military attack" .)

I've seen this clue in The Telegraph and The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.