Rubbish spread about hideout of groundhog, say (6)
I believe the answer is:
rodent
'groundhog say' is the definition.
(I know that Marmota monax is a type of marmot)
'rubbish spread about hideout' is the wordplay.
'rubbish' becomes 'rot' (both can mean nonsense).
'spread about' indicates putting letters inside.
'hideout' becomes 'den' (synonyms).
'rot' placed around 'den' is 'RODENT'.
'of' is the link.
(Other definitions for rodent that I've seen before include "E.g. hamster" , "Animal such as a mouse" , "Creature such as a rat" , "Vermin" , "Rat perhaps" .)