Just by real ground (6)
I believe the answer is:
barely
'just' is the definition.
(barely can mean only just)
'by real ground' is the wordplay.
'ground' is an anagram indicator ('grind' the letters into a new form).
'by'+'real'='byreal'
'byreal' anagrammed gives 'BARELY'.
(Other definitions for barely that I've seen before include "just a short while before" , "how streakers like to act?" , "how babies are born?" , "Not quite" , "Just about or scantily" .)