Notice one in tirade incandescent (7)
I believe the answer is:
radiant
'incandescent' is the definition.
(I've seen this before)
'notice one in tirade' is the wordplay.
'notice' becomes 'ad'.
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'tirade' becomes 'rant' (I've seen this before).
'ad'+'i'='adi'
'adi' going into 'rant' is 'RADIANT'.
(Other definitions for radiant that I've seen before include "Very conspicuous" , "Luminous" , "glowing with happiness" , "Effulgent" , "Incandescent" .)