Mammals long for change, beset by troubles (9)

'mammals' is the definition.
(pangolin is a kind of mammal)

'long for change beset by troubles' is the wordplay.
'for change' indicates anagramming the letters (I've seen this in other clues).
'beset by' indicates putting letters inside ('beset' could historically mean 'cover').
'troubles' becomes 'pains' ('pain' can be a synonym of 'trouble').
'long' with letters rearranged gives 'ngol'.
'ngol' placed inside 'pains' is 'PANGOLINS'.