Small number with team backing US inventor (6)
I believe the answer is:
edison
'us inventor' is the definition.
(Thomas Edison)
'small number with team backing' is the wordplay.
'small number' becomes 'no' (abbreviation for 'number'; 'small' indicates an abbreviation).
'with' says to put letters next to each other.
'team' becomes 'side' (both can mean a sports team).
'backing' says the letters should be written backwards.
'no'+'side'='noside'
'noside' reversed gives 'EDISON'.
(Other definitions for edison that I've seen before include "Onside with great American inventor" , "Thomas --, US?inventor" , "He came up with microphone" , "No side to this american inventor" , "Early American inventor" .)