Have unpleasant thoughts about animal sick with desire (4,3,4)
I believe the answer is:
bear ill will
'desire' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'have unpleasant thoughts about animal sick with' is the wordplay.
I cannot quite see how this works, but
'have' could be 'bear' (synonyms) and 'bear' is found in the answer.
'unpleasant' could be 'ill' (feeling ill is feeling unpleasant) and 'ill' is found in the answer.
'sick' could be 'ill' (similar in meaning) and 'ill' is present in the answer.
'with' could be 'w' (short for with) and 'w' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for bear ill will that I've seen is " Wish someone harm".)