One gets lb50 for the lot (3)
I believe the answer is:
all
'the lot' is the definition.
(I've seen this in another clue)
'one gets lb50' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'gets' means one lot of letters go next to another.
'lb50' becomes 'll' (I can't explain this - if you can you should believe this answer much more).
'a'+'ll'='ALL'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for all that I've seen before include "'Bless 'em - - ' (song)" , "Comprising every individual one" , "Monopolist controls this" , "that's as many as there are" , "Avenue, walk or garden path" .)