Look old, clutching book in summerhouse (6)
I believe the answer is:
gazebo
'summerhouse' is the definition.
('gazebo' can be a synonym of 'summerhouse')
'look old clutching book' is the wordplay.
'look' becomes 'gaze' (gaze is a kind of look**).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'clutching' means one lot of letters goes inside another.
'book' becomes 'b'.
'gaze'+'o'='gazeo'
'gazeo' placed around 'b' is 'GAZEBO'.
'in' is the link.
(Other definitions for gazebo that I've seen before include "Raised summerhouse with a wide view" , "outhouse" , "Garden sumer-house with wide view" , "Summerhouse with views" , "Small garden house with a view" .)