Sharks, for example, are so allied (2,6)
I believe the answer is:
in league
'allied' is the definition.
(thesaurus)
'sharks for example are' is the wordplay.
I cannot really understand how this works, but
'are' could be 'a' (short for 'are', historical unit of measurement) and 'a' is found in the answer.
'example' could be 'eg' (short for 'exempli gratia', 'for example' in Latin) and 'eg' is found within the remaining letters.
This explanation may well be incorrect...
'so' is the link.
Can you help me to learn more?
(Other definitions for in league that I've seen before include "belonging to a competitive group of teams" , "Working together" , "as teams usually are" , "Co-operating" , "Collaborating" .)