Young woman almost finding major deceptive (10)
I believe the answer is:
misleading
'deceptive' is the definition.
(I know that deceptive can be written as misleading)
'young woman almost finding major' is the wordplay.
'young woman' becomes 'miss' (title for a young woman).
'almost' means to remove the last letter (most of the word but not all of it).
'finding' says to put letters next to each other.
'major' becomes 'leading' (similar in meaning).
'miss' with its final letter taken away is 'mis'.
'mis'+'leading'='MISLEADING'
(Other definitions for misleading that I've seen before include "Giving a wrong impression" , "pointing in the wrong direction" , "Giving a false impression" , "Deceptive" , "Unreliable" .)