Sarcasm in press secretary’s conclusion (5)
I believe the answer is:
irony
'sarcasm' is the definition.
(synonyms)
'press secretary's conclusion' is the wordplay.
'press' becomes 'iron' (ironing is a kind of pressing).
'conclusion' indicates one should take the final letters.
The last letter of 'secretary' is 'y'.
'iron'+'y'='IRONY'
'in' acts as a link.
(Other definitions for irony that I've seen before include "Socratic method of discussion" , "It could be hard" , "What "as clear as mud" demonstrates" , "Sarcastic humour" , "the reverse of what you'd expect" .)