Black duck on watch in summerhouse (6)
I believe the answer is:
gazebo
'summerhouse' is the definition.
(I know that Gazebo is a summerhouse)
'black duck on watch' is the wordplay.
'black' becomes 'b' (abbreviation as in pencil hardness).
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'on' means one lot of letters go next to another.
'watch' becomes 'gaze' (I can't justify this - if you can you should give a lot more credence to this answer).
'b'+'o'='bo'
'bo' put after 'gaze' is 'GAZEBO'.
'in' is the link.
Can you help me to learn more?
(Other definitions for gazebo that I've seen before include "garden feature" , "Kind of garden summerhouse with wide view" , "Summerhouse with a good view" , "Small garden house with a view" , "Small summerhouse for shade" .)