Not half easy navigating two-master that's slight (7)
I believe the answer is:
sketchy
'slight' is the definition.
(synonyms)
'not half easy navigating two-master' is the wordplay.
'not half' indicates taking half.
'navigating' means one lot of letters goes inside another.
'two-master' becomes 'ketch' (I've seen this in another clue).
'easy' with half the letters taken is 'sy'.
'sy' going around 'ketch' is 'SKETCHY'.
'that's' acts as a link.
(Other definitions for sketchy that I've seen before include "Incomplete; rough" , "lacking detail" , "Imperfect" , "Not thorough or detailed" , "first draft" .)