Car seat is assembled using series of steps (9)
I believe the answer is:
staircase
'series of steps' is the definition.
'staircase' can be an answer for 'steps' (I've seen this before). I'm not certain of the 'series of' bit.
'car seat is assembled' is the wordplay.
'assembled' is an anagram indicator.
'car'+'seat'+'is'='carseatis'
'carseatis' is an anagram of 'STAIRCASE'.
'using' acts as a link.
Can you help me to learn more?
(Other definitions for staircase that I've seen before include "It's Caesar (anag.)" , "Set of steps" , "Group of joined locks on a canal" , "Situation of flight" , "A group of linked canal locks" .)