Right time to lose one's temper (4)
I believe the answer is:
rage
'lose one's temper' is the definition.
(I've seen this in another clue)
'right time' is the wordplay.
'right' becomes 'r' (abbreviation).
'time' becomes 'age' (an age is a period of time).
'r'+'age'='RAGE'
'to' acts as a link.
(Other definitions for rage that I've seen before include "Fit of anger" , "Fit of temper" , "Craze, fad" , "a poetic response to dying light?" , "See red" .)