In diplomacy I find it's understood (5)
I believe the answer is:
tacit
'it's understood' is the definition.
(I've seen this before)
'in diplomacy i' is the wordplay.
'in' indicates putting letters inside.
'diplomacy' becomes 'tact' (tact can mean diplomacy or sensitivity).
'tact' enclosing 'i' is 'TACIT'.
'find' acts as a link.
(Other definitions for tacit that I've seen before include "Wordless" , "Implicitly understood" , "Unspoken but implied" , "Implied -- inferred" , "Understood, implicit" .)