Former husband a metre out from the furthest point (7)
I believe the answer is:
extreme
'the furthest point' is the definition.
(I've seen this before)
'former husband a metre out' is the wordplay.
'former husband' becomes 'ex' (an ex-husband).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'metre' anagrammed gives 'treme'.
'ex'+'treme'='EXTREME'
'from' is the link.
(Other definitions for extreme that I've seen before include "Anything but moderate" , "Very serious" , "Draconian" , "Last" , "Very great; not usual" .)