Worker interrupting start of this odd outburst (7)
I believe the answer is:
tantrum
'outburst' is the definition.
(I've seen this before)
'worker interrupting start of this odd' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'interrupting' is an insertion indicator.
'start of' says to take the initial letters.
'odd' becomes 'rum' (I've seen this before).
The first letter of 'this' is 't'.
't'+'rum'='trum'
'ant' going within 'trum' is 'TANTRUM'.
(Other definitions for tantrum that I've seen before include "Wobbly" , "Display of bad temper" , "Child's outburst of bad temper" , "fit of bad temper" , "throwing this?" .)