Eccentric fixed outside step with rake (5,5)
I believe the answer is:
space cadet
'eccentric' is the definition.
(space cadet can mean an eccentric person)
'fixed outside step with rake' is the wordplay.
'fixed' becomes 'set' (both can mean decided or determined).
'outside' is an insertion indicator.
'step' becomes 'pace' (synonyms).
'with' is a charade indicator (letters next to each other).
'rake' becomes 'cad' (I've seen this in another clue).
'pace'+'cad'='pacecad'
'set' going around 'pacecad' is 'SPACE CADET'.
(Other definitions for space cadet that I've seen before include "trainee astronaut" , "one who often gets high" , "one high on drugs" .)