One of the yahoos in 27 across and 8 down (6,6)
I believe the answer is:
search engine
'one of the yahoos' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'in 27 across and 8 down' is the wordplay.
I cannot quite see how this works, but
'in' is present in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for search engine that I've seen before include "internet facility" , "Yahoo or Google. for example" , "Online helper" , "Program for locating information" .)