Top grade carbon copy's acquired quickly (5)
I believe the answer is:
apace
'quickly' is the definition.
(synonyms)
'top grade carbon copy's acquired' is the wordplay.
'top grade' becomes 'a'.
'carbon' becomes 'c' (C is the chemical symbol for carbon).
'copy' becomes 'ape' (synonyms).
'acquired' is an insertion indicator.
'a'+'c'='ac'
'ac' placed inside 'ape' is 'APACE'.
(Other definitions for apace that I've seen before include "(Move on) swiftly" , "at high speed" , "What's quickly" , "flat out" , "Quick" .)