The very same day I returned, a client exploded (9)
I believe the answer is:
identical
'the very same' is the definition.
(I've seen this before)
'day i returned a client exploded' is the wordplay.
'day' becomes 'd'.
'returned' is a reversal indicator.
'exploded' is an anagram indicator.
'd'+'i'='di'
'di' back-to-front is 'id'.
'a'+'client'='aclient'
'aclient' anagrammed gives 'entical'.
'id'+'entical'='IDENTICAL'
(Other definitions for identical that I've seen before include "as B and B" , "Impossible to tell apart" , "lacking distinction" , "Aid client to be the very same" , "showing no change" .)