Cool rector comes in to fix small steps (10)

'small steps' is the definition.
Although both the answer and definition are plural nouns, I can't understand how they can define each other.

'cool rector comes in to fix' is the wordplay.
'cool' becomes 'in' ('in' can mean fashionable or cool).
'rector' becomes 'r'.
'comes in to' indicates putting letters inside.
'fix' becomes 'cements' (I can't justify this - if you can you should believe this answer much more).
'r' put into 'cements' is 'crements'.
'in'+'crements'='INCREMENTS'

Can you help me to learn more?