Place for aircraft no good in sea fog (6)
I believe the answer is:
hangar
'place for aircraft' is the definition.
(aircraft are stored in hangars)
'no good in sea fog' is the wordplay.
'no good' becomes 'ng' (abbreviation).
'in' indicates putting letters inside.
'sea fog' becomes 'haar' (I've seen this before).
'ng' going into 'haar' is 'HANGAR'.
(Other definitions for hangar that I've seen before include "Airport building" , "Airfield building" , "Structure where aircraft are maintained" , "Aircraft shelter" , "Large shed to house aircraft" .)