Hazy account kept by single following (7)
I believe the answer is:
inexact
'hazy' is the definition.
(thesaurus)
'account kept by single following' is the wordplay.
'account' becomes 'ac'.
'kept by' means one lot of letters goes inside another.
'single' becomes 'i' (one).
'following' becomes 'next' ('next' can be a synonym of 'following'**).
'i'+'next'='inext'
'ac' placed inside 'inext' is 'INEXACT'.
(Other definitions for inexact that I've seen before include "Not quite right" , "Not quite accurate" , "Not entirely accurate" , "not wholly Right" , "estimated?" .)