Plant business barely increased activity to begin with (12)
I believe the answer is:
tradescantia
'plant' is the definition.
The answer is an example.
'business barely increased activity to begin with' is the wordplay.
'business' becomes 'trade' (trade is a kind of business).
'barely' becomes 'scant'.
'to begin with' suggests taking the first letters.
The first letters of 'increased activity' is 'ia'.
'trade'+'scant'+'ia'='TRADESCANTIA'
(Other definitions for tradescantia that I've seen before include "Common house plant" , "Spiderwort genus" , "Common houseplant" .)