A smaller amount at the start, with even fewer afterwards - it's decreasing continually (4,3,4)

'afterwards it's decreasing continually' is the definition.
I can't tell whether this defines the answer.

'a smaller amount at the start with even fewer' is the wordplay.
'a smaller amount' becomes 'less' (I've seen this in another clue).
'at the start' is a charade indicator (letters next to each other).
'with' becomes 'and'.
'even fewer' becomes 'less' (associated in meaning. I am not sure about the 'even' bit.).
'less'+'and'+'less'='LESS AND LESS'

Can you help me to learn more?