Conclusion to clash, indeed, that’s cut and dried! (3)
I believe the answer is:
hay
'that's cut and dried' is the definition.
(hay is dried-out grass)
'conclusion to clash indeed' is the wordplay.
'conclusion to' says to take the final letters.
'indeed' becomes 'ay' ('ay' and 'aye' can mean yes).
The last letter of 'clash' is 'h'.
'h'+'ay'='HAY'
(Other definitions for hay that I've seen before include "Welsh festival" , "basic bedding" , "Animal fodder" , "Straw" , "Wye book town" .)