Standard thus ensued case of bacteria (5)
I believe the answer is:
basic
'standard' is the definition.
(similar in meaning)
'thus ensued case of bacteria' is the wordplay.
I cannot really understand how this works, but
'thus' could be 'sic' ('thus' in Latin) and 'sic' is present in the answer.
The remaining letters 'ba' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for basic that I've seen before include "Simple form of language" , "Fundamental, elementary" , "Elementary - without extras" , "'Primary, fundamental (5)'" , "Key" .)