Man for one in Doris Lessing (4)
I believe the answer is:
isle
'man for one' is the definition.
(I've seen this before)
'in doris lessing' is the wordplay.
'in' indicates a hidden word.
'ISLE' is hidden in the letters of 'doris lessing'.
(Other definitions for isle that I've seen before include "eg Capri" , "Land amid water" , "Detached place" , "description of Britain" , "Land surrounded entirely by water" .)