Charge including many a collection of boats (8)
I believe the answer is:
flotilla
'collection of boats' is the definition.
(a flotilla is a collection of boats)
'charge including many a' is the wordplay.
'charge' becomes 'fill' (I've seen this in other clues).
'including' indicates putting letters inside.
'many' becomes 'lot' (a lot of something).
'fill' placed around 'lot' is 'flotill'.
'flotill'+'a'='FLOTILLA'
(Other definitions for flotilla that I've seen before include "A lot of craft" , "Group of boats or small warships" , "number of vessels" , "Small group of ships" , "Fleet of small craft" .)