That Rodney, fooling about! (6)
I believe the answer is:
yonder
'that' is the definition.
(archaic word meaning 'that')
'rodney fooling about' is the wordplay.
'fooling about' indicates anagramming the letters.
'rodney' is an anagram of 'YONDER'.
(Other definitions for yonder that I've seen before include "At a distance but in sight" , "Rodney (anag.)" , "Over there (poetic)" , "that one" , "Over there, of old." .)