Lone victor goes in to find the answer (5)
I believe the answer is:
solve
'find the answer' is the definition.
(I've seen this before)
'lone victor goes in' is the wordplay.
'lone' becomes 'sole' (synonyms).
'victor' becomes 'V' (phonetic alphabet: alpha, bravo, charlie etc.).
'goes in' means one lot of letters goes inside another.
'sole' placed around 'v' is 'SOLVE'.
'to' acts as a link.
(Other definitions for solve that I've seen before include "as you're trying to do now" , "Unravel (a problem)" , "Find the answer to this clue, for instance" , "Find the answer or explanation" , "Decipher" .)