What the wind does brings lake into front of boat (4)
I believe the answer is:
blow
'what the wind does' is the definition.
(the wind blows)
'lake into front of boat' is the wordplay.
'lake' becomes 'L' (geographical abbreviation).
'into' is an insertion indicator.
'front of boat' becomes 'bow' (nautical term).
'l' placed into 'bow' is 'BLOW'.
'brings' acts as a link.
(Other definitions for blow that I've seen before include "fluff" , "Gust" , "Cuff" , "Strong current of air" , "Breathe hard" .)