Animals collectively creep, it's said (5)
I believe the answer is:
fauna
'animals collectively' is the definition.
(I've seen this in another clue)
'creep it's said' is the wordplay.
'creep' becomes 'fawner' (someone who fawns over others).
'it's said' indicates a 'sounds like' (homophone) clue.
'fawner' is a homophone of 'FAUNA'.
(Other definitions for fauna that I've seen before include "Animal life of given region" , "Wild animal life of an era" , "(Region's) animal life" , "list of animal life" , "Animals of an area or period" .)