Work unit essential for creating synergies (3)
I believe the answer is:
erg
'work unit' is the definition.
(I know that erg is a type of work unit)
'essential for creating synergies' is the wordplay.
'essential for' indicates the answer is hidden within the clue (I've seen this in other clues).
'ERG' is hidden in the letters of 'creating synergies'.
(Other definitions for erg that I've seen before include "Unit of work or energy" , "Amount of work" , "Unit of work; dunes area" , "Unit of work (phys.)" , "Energy expended" .)