Those at work in a position of responsibility (3,4)
I believe the answer is:
hot seat
'a position of responsibility' is the definition.
(I've seen this before)
'those at work' is the wordplay.
'work' is an anagram indicator.
'those'+'at'='thoseat'
'thoseat' anagrammed gives 'HOT SEAT'.
'in' acts as a link.
(Other definitions for hot seat that I've seen before include "Position carrying full responsibility" , "Position of full responsibility (colloq.)" , "Position at top" , "from which bottom quick to rise?" , "Situation of responsibility or danger" .)