Agitation of whistleblower turning workers tense (7)
I believe the answer is:
ferment
'agitation' is the definition.
(I know that agitation can be written as ferment)
'whistleblower turning workers tense' is the wordplay.
'whistleblower' becomes 'ref' (a referee blows a whistle).
'turning' is a reversal indicator.
'workers' becomes 'men' (men can mean staff or employees).
'tense' becomes 't' (abbreviation used in many dictionaries).
'ref' in reverse letter order is 'fer'.
'fer'+'men'+'t'='FERMENT'
'of' is the link.
(Other definitions for ferment that I've seen before include "Seething commotion" , "Stir up" , "Undergo chemical reaction such as when sugar turns to alcohol" , "tizzy" , "Agitation, turbulence" .)