Send Tom out furthest (7)
I believe the answer is:
endmost
'furthest' is the definition.
(at the furthest end)
'send tom out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'send'+'tom'='sendtom'
'sendtom' with letters rearranged gives 'ENDMOST'.
(Other definitions for endmost that I've seen before include "Last in a row" , "extreme situation" , "final" , "Furthest away" , "Last in the line" .)