After limitless time, step in without delay (9)
I believe the answer is:
immediate
'without delay' is the definition.
(I've seen this before)
'after limitless time step' is the wordplay.
'after' says to put letters next to each other.
'limitless' says to take the centre.
'step' becomes 'mediate' (I am not sure about this - if you are sure you should believe this answer much more).
The middle of 'time' is 'im'.
'im'+'mediate' is 'IMMEDIATE'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for immediate that I've seen before include "Instantaneous" , "Most urgent; current" , "Present" , "Prompt, straightaway" , "Prompt,straightaway" .)