Hippo delightedly entertains whale group (3)
I believe the answer is:
pod
'whale group' is the definition.
(I've seen this in another clue)
'hippo delightedly entertains' is the wordplay.
'entertains' says the answer is hidden in the clue (the answer is welcomed or entertained by the clue).
'POD' can be found hidden inside 'hippo delightedly'.
(Other definitions for pod that I've seen before include "Seed carrier (eg, pea)" , "A pea grows in it" , "Small school of whales" , "Seed case of peas" , "Group of whales" .)