Palpable lie ruined by diplomacy (7)
I believe the answer is:
tactile
'palpable' is the definition.
(thesaurus)
'lie ruined by diplomacy' is the wordplay.
'ruined' is an anagram indicator.
'by' says to put letters next to each other.
'diplomacy' becomes 'tact' (I've seen this before).
'lie' is an anagram of 'ile'.
'ile' after 'tact' is 'TACTILE'.
(Other definitions for tactile that I've seen before include "Cattle I find with sense of touch" , "Based on the sense of touch" , "Tangible - of touch" , "be felt" , "Touchy" .)