Abstemious office worker's energy and speed (9)
I believe the answer is:
temperate
'abstemious' is the definition.
(similar in meaning)
'office worker's energy and speed' is the wordplay.
'office worker' becomes 'temp' (I've seen this before).
'energy' becomes 'e' (physics symbol as in E=mc2).
'and' is a charade indicator (letters next to each other).
'speed' becomes 'rate' (the speed at which something is happening).
'temp'+'e'+'rate'='TEMPERATE'
(Other definitions for temperate that I've seen before include "Moderate, mild" , "comfortably warm?" , "Showing self-restraint" , "sober" , "with balmy climate" .)