A time to tease in long rant (8)
I believe the answer is:
diatribe
'rant' is the definition.
(I've seen this before)
'a time to tease in long' is the wordplay.
'time' becomes 't' (abbreviation).
'to tease' becomes 'rib' (rib can mean to tease or mock).
'in' indicates putting letters inside.
'long' becomes 'die' (to long for or to die for something is to crave it).
'a'+'t'+'rib'='atrib'
'atrib' going into 'die' is 'DIATRIBE'.
(Other definitions for diatribe that I've seen before include "Bitter words" , "A prolonged tirade or abusive speech" , "I debar it, being a violent attack in words" , "Torrent of abuse" , "stream of abuse" .)