Work requires some internal cooperation (5)
I believe the answer is:
opera
'work' is the definition.
(musical work)
'some internal cooperation' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'OPERA' can be found hidden inside 'internal cooperation'.
'requires' acts as a link.
(Other definitions for opera that I've seen before include "The Magic Flute, say" , "Musical piece accompanying a stage drama or comedy" , "Eg, Don Giovanni" , "Tosca, for example" , "Musical theatre work" .)