Putting in fortune, load a fleet (8)

I believe the answer is:

flotilla

I'm a little stuck... Click here to teach me more about this clue!

'fleet' is the definition.
(I know that flotilla is a type of fleet)

'putting in fortune load a' is the wordplay.
'putting in' indicates putting letters inside.
'fortune' becomes 'lot' (as in a person's lot in life).
'load' becomes 'fill' (I can't justify this - if you can you should believe this answer much more).
'lot' inserted within 'fill' is 'flotill'.
'flotill'+'a'='FLOTILLA'

Can you help me to learn more?

(Other definitions for flotilla that I've seen before include "number of vessels" , "Fleet of small craft" , "number of boats" , "A lot of craft" , "Small group of ships" .)

I've seen this clue in The Sun and The Times.

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