Eccentric comedian with no energy is wandering (7)
I believe the answer is:
nomadic
'is wandering' is the definition.
('nomadic' can be a synonym of 'wandering')
'eccentric comedian with no energy' is the wordplay.
'eccentric' indicates an anagram.
'with no' indicates named letters should be taken away.
'energy' becomes 'e' (physics symbol as in E=mc2).
'comedian' with 'e' taken out is 'comdian'.
'comdian' is an anagram of 'NOMADIC'.
(Other definitions for nomadic that I've seen before include "Homeless - wandering" , "migrant" , "Roaming" , "always moving?" , "Given to wandering like travellers or Bedouins" .)