I do business - perfect! (5)
I believe the answer is:
ideal
'perfect' is the definition.
(similar in meaning)
'i do business' is the wordplay.
'do business' becomes 'deal' (as in doing a business deal).
'i'+'deal'='IDEAL'
(Other definitions for ideal that I've seen before include "Exemplary" , "Cutting/stabbing weapons" , "Benchmark" , "fanciful" , "Optimal" .)