Mood of agency worker here in centre (6)
I believe the answer is:
temper
'mood' is the definition.
(temper is one's mood or state of mind)
'agency worker here in centre' is the wordplay.
'agency worker' becomes 'temp' (temporary worker sent from an agency).
'in centre' says to take the centre.
The central letters of 'here' are 'er'.
'temp'+'er'='TEMPER'
'of' is the link.
(Other definitions for temper that I've seen before include "Tendency to anger" , "Tendency to become angry easily" , "Tantrum" , "Modify" , "Irritability" .)