US college groups picked up kind of marine creature (8)
I believe the answer is:
starfish
'marine creature' is the definition.
(I know that starfish is a type of marine creature)
'us college groups picked up kind of' is the wordplay.
'us college groups' becomes 'frats' (fraternities).
'picked up' says the letters should be written backwards.
'kind of' becomes 'ish' (eg cheapish means kind of cheap).
'frats' written backwards gives 'starf'.
'starf'+'ish'='STARFISH'
(Other definitions for starfish that I've seen before include "Well-armed customer" , "Heavenly marine animal?" , "One found at sea" , "Has rifts (anag)" , "As swimmer" .)