Inventor would arrange test tubes for starters (4)
I believe the answer is:
watt
'inventor' is the definition.
(Scottish inventor James Watt)
'would arrange test tubes for starters' is the wordplay.
'for starters' indicates taking the first letters.
The first letters of 'would arrange test tubes' is 'WATT'.
(Other definitions for watt that I've seen before include "bit of power" , "Light bulb unit" , "Work rate" , "James - - (Scottish inventor)" , "James -; Sc. engineer" .)