Slow progress by leader, favoured to ascend in depth? (4,5)

'slow progress' is the definition.
I know nothing about this answer so I can't tell whether this works.

'by leader favoured to ascend in depth?' is the wordplay.
'leader' says to take the initial letters.
'favoured' becomes 'pet' (as in a pet project).
'to ascend' is a reversal indicator (I've seen 'ascending' mean this).
'in' means one lot of letters goes inside another.
'depth?' becomes 'abyss' (I've seen this in another clue).
The first letter of 'by' is 'b'.
'pet' backwards is 'tep'.
'tep' put into 'abyss' is 'abysteps'.
'b'+'abysteps'='BABY STEPS'

Can you help me to learn more?