What you're trying to do, alone, very engrossed (5)
I believe the answer is:
solve
'what you're trying to do' is the definition.
(I've seen this in another clue)
'alone very engrossed' is the wordplay.
'alone' becomes 'sole' (synonyms).
'very' becomes 'v' (abbreviation).
'engrossed' indicates putting letters inside.
'sole' enclosing 'v' is 'SOLVE'.
(Other definitions for solve that I've seen before include "Clear up a mystery" , "Find an answer to (a problem)" , "Decipher" , "Find the key - work out" , "Unravel (a clue)" .)