Start to brick in the second man's hut (5)
I believe the answer is:
cabin
'hut' is the definition.
(I've seen this before)
'start to brick in the second man's' is the wordplay.
'start to' indicates taking the first letters.
'in the' means one lot of letters goes inside another.
'second man' becomes 'cain' (biblical second man after Adam).
The initial letter of 'brick' is 'b'.
'b' inserted within 'cain' is 'CABIN'.
(Other definitions for cabin that I've seen before include "Railway signal box" , "Room on board ship" , "Wooden hut" , "place on board" , "Private room aboard" .)