Style of humour (5)
I believe the answer is:
irony
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">style of humour</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for irony that I've seen before include "Satire, sarcasm" , "Figure of speech" , "Kind of sarcasm, sounds metallic" , "Use of words to convey the opposite of what they normally mean" , "Gentle sarcasm" .)