Work on it perhaps as a possibility (6)
I believe the answer is:
option
'a possibility' is the definition.
(I've seen this before)
'work on it perhaps' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'perhaps' indicates anagramming the letters.
'on'+'it'='onit'
'onit' is an anagram of 'tion'.
'op'+'tion'='OPTION'
'as' acts as a link.
(Other definitions for option that I've seen before include "Choice of portion" , "Something that may be chosen" , "Choice, selection" , "Something choosable" , "Possible choice" .)