Temper iron, not using right equipment initially (5)
I believe the answer is:
inure
'temper' is the definition.
(I've seen this in another clue)
'iron not using right equipment initially' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'iron not using right equipment' is 'INURE'.
(Other definitions for inure that I've seen before include "Harden against, make tough" , "Cause to become hardened to" , "harden attitude" , "Harden or accustom as to something unpleasant" , "Accustom (someone) to something unpleasant" .)