Little case enclosing the unique implement, for starters (4)
I believe the answer is:
'little case' is the definition.
'etui' can be an answer for 'case' (I've seen this before). I am not sure about the 'little' bit.
'enclosing the unique implement for starters' is the wordplay.
'for starters' says to take the initial letters.
The initial letters of 'enclosing the unique implement' is 'ETUI'.
Can you help me to learn more?
(Other definitions for etui that I've seen before include "Small French case" , "Case containing sharp objects" , "box" , "Case for holding sewing articles" , "Tiny ladies' bag" .)