Endlessly surprised by web (4)
I believe the answer is:
maze
'web' is the definition.
(thesaurus)
'endlessly surprised' is the wordplay.
'endlessly' means to look at the middle letters (the ends of the words are removed).
'surprised' becomes 'amazed' (amazing is a kind of surprising).
The middle letters of 'amazed' are 'MAZE'.
'by' acts as a link.
(Other definitions for maze that I've seen before include "confusion" , "A labyrinth of hedges - easy to get lost in" , "Complex network" , "Puzzling network of paths" , "Confusing network of paths" .)