Having seen day well out with cheese (11)
I believe the answer is:
wensleydale
'cheese' is the definition.
(I've seen this before)
'having seen day well out' is the wordplay.
'seen day well' anagrams to 'WENSLEYDALE'.
But, I'm not clear how this is indicated.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for wensleydale that I've seen before include "Say, we'll need (anag); a cheese" , "Yorkshire cheese" , "White crumbly variety of cheese" , "Type of white cheese" , "Wallace's favourite cheese" .)