Gruel I cooked is more unpleasant (6)
I believe the answer is:
uglier
'more unpleasant' is the definition.
Both the answer and definition are comparative adjectives. Maybe you can see an association between them that I can't see?
'gruel i cooked' is the wordplay.
'cooked' indicates an anagram (letters cooked into a new form).
'gruel'+'i'='grueli'
'grueli' anagrammed gives 'UGLIER'.
'is' is the link.
Can you help me to learn more?
(Other definitions for uglier that I've seen before include "More hideous" , "More displeasing to the sight" , "More unsightly" , "with worse features" , "More lacking in beauty" .)