Start what I did in restaurant (8)
I believe the answer is:
initiate
'start' is the definition.
(I know that initiate is a action)
'i did in restaurant' is the wordplay.
I cannot quite understand how this works, but
'i' could be 'a' and 'a' is present in the answer.
'in' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'what' acts as a link.
Can you help me to learn more?
(Other definitions for initiate that I've seen before include "accept new members" , "Admit, to a secret society say" , "Cause to begin or admit to membership" , "Begin or admit into a closed society" , "Start, launch" .)