Displeased, being infested? (5)
I believe the answer is:
ratty
'infested?' is the definition.
(thesaurus)
'displeased being' is the wordplay.
I cannot really understand how this works, but
'being' could be 'rat' (rat is a kind of being) and 'rat' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ratty that I've seen before include "Irritable, peevish" , "his friend being a dangerous driver" , "Get annoyed" , "Fictional mole's chum" , "with pests" .)