Liking corn mashed up isn't English attitude (14)
I believe the answer is:
sentimentality
'liking corn' is the definition.
(a liking for corny things)
'isn't english attitude' is the wordplay.
'isn't english' becomes 'senti' (I can't explain this - if you can you should believe this answer much more).
'attitude' becomes 'mentality' (mentality is a kind of attitude).
'senti'+'mentality'='SENTIMENTALITY'
'mashed up' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
(Other definitions for sentimentality that I've seen before include "Slush" , "Gooey feeling" .)