Unit of magnetic flux (7)
I believe the answer is:
maxwell
'unit of magnetic flux' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for maxwell that I've seen before include "James Clerk --, Scottish physicist" , "Pioneer of electromagnetism - Czech-born tycoon" , "Scottish scientist" , "Victorian scientist" , "Robert, once a press baron" .)