Delight as first of properties let (6)
I believe the answer is:
please
'delight' is the definition.
('please' can be a synonym of 'delight')
'first of properties let' is the wordplay.
'first of' indicates taking the first letters.
'let' becomes 'lease' ('lease' can be a synonym of 'let').
The first letter of 'properties' is 'p'.
'p'+'lease'='PLEASE'
'as' is the link.
(Other definitions for please that I've seen before include "if you don't mind" , "(Word used in) asking or accepting politely" , "Satisfy while asleep" , "Elapse (anag.)" , "Like" .)