You're aiming to do it alone, with very little input (5)
I believe the answer is:
solve
'you're aiming to do it' is the definition.
(you are currently solving a crossword)
'alone with very little input' is the wordplay.
'alone' becomes 'sole' (synonyms).
'with' indicates putting letters inside.
'very little input' becomes 'v' (I can't explain this - if you can you should give a lot more credence to this answer).
'sole' placed around 'v' is 'SOLVE'.
(Other definitions for solve that I've seen before include "Clear up a mystery" , "Explain (a mystery)" , "as you're trying to do now" , "Deal with (a problem)" , "Find an answer to (a problem)" .)