Close friend's misshapen large toe (5,3)
I believe the answer is:
alter ego
'close friend's' is the definition.
'misshapen large toe' is the wordplay.
'misshapen' indicates an anagram.
'large'+'toe'='largetoe'
'largetoe' is an anagram of 'ALTER EGO'.
(Other definitions for alter ego that I've seen before include "Similar character" , "Change conceit for other self" , "To regale other self" , "One's secondary personality" , "Hidden self or very close friend" .)